- Availability of Classroom Music
- Teachers’ Qualifications and Demographics
- Prior and Current Musical Activities
- Teaching and Training Experience
- Teacher Confidence and Related Perceptions
- Areas Needing Improvement
- Final Comments
This article presents a statistical analysis of secondary school music in Australia based on Irina Petrova’s doctoral dissertation published in 2012. It continues from the initial description of her work in” Major Research into School Music Education” and Primary School Music Teaching. The first article was based on Petrova’s two articles in Music Forum, dated November 2012 and February 2013 and dealing with primary and secondary schools, respectively. This is the third and last article in this statistically oriented knowledge base series.
The content is primarily statistical because the knowledge base faces a major challenge to assemble a comprehensive numerical picture of the music sector, and school music education is statistically a major neglected topic. The article deals in turn with the following topics:1
- Availability of Classroom Music
- Teacher Qualifications and Demographics
- Prior and Current Musical Activities
- Teaching and Training Experience
- Teacher Confidence and Related Perceptions
- Areas Needing Improvement.
The article takes a critical look at statistical quality, focusing on the distribution across states and territories but also on the bias towards larger schools which is especially prevalent in the secondary school sample (see next section).
By an extraordinary coincidence, the final work to prepare this series of articles based on Irina Petrova’s thesis for the MCA knowledge base coincided within hours with the launch of the Australian government’s national cultural policy, which includes making the arts an official part of the Australian school curriculum as an important plank in the policy platform. The last section of this article, Final Comments, expresses the hope that her thesis will help to demonstrate, in no uncertain terms, the need to act quickly and decisively to remedy what could otherwise be a major hurdle against the implementation of the new national policy.
The table numbering starts from 19 and the chart numbering from 7, continuing the sequence from Primary School Music Teaching.
Availability of Classroom Music
Table 1 at the end of Major Research into School Music Education showed that Petrova reached 91% of all secondary schools in Australia (2,466). Of these, 833 had no classroom music teaching (33.7%). Disconcertingly, of the 1,633 schools that did offer classroom music, 1,026 of the principals contacted (63%) did not permit her to approach teachers. This means that 41.6% of the total number of schools reached couldn’t be included in the survey, leaving only 607 secondary schools available for this part of her research (24.6% of total schools reached). Though the response rate among teachers contacted in these schools was better than for the primary schools (23.2% as against 18.4%), only 141 surveys were completed compared with 258 in primary schools.
The largest number of completed surveys came from New South Wales (56), followed by Victoria (28), Queensland (21), South Australia (13), Tasmania (8), Western Australia and the Australian Capital Territory (5 each), and the Northern Territory (1). The location of the remaining four schools is not known.
The left-hand box compares the actual distributions across states and territories of secondary schools and the combined primary and secondary schools which were included in both samples, with the distribution of the 137 schools in Petrova’s sample for which the location was known. The ratio of combined to total secondary schools varies from 36% in NSW and 38% in Victoria to 49% in Queensland, 56% in Tasmania, 60% in South Australia and 63% in Western Australia, which may cause bias in the sampling procedure. The ratio seems to be influenced to some extent by population size and possibly also the relative influence of the rural and remote hinterland. It was a relatively modest 46% in the ACT and highest of all in the Northern Territory (77%).
It is unclear whether the proportion of combined schools had much influence on the distribution that resulted from Petrova’s secondary school survey. NSW with its relatively small percentage of combined schools is over-represented in the survey, and Western Australia, the most under-represented state, has the highest percentage of these schools among the states. Apart from this the picture is blurred because the dominant factor is the modest size of the secondary school sample across the states and territories which is the source of considerable sampling error causing uncertainty in the validity of the findings.
It may be technically possible to fix some flaws assuming Petrova’s database remains intact, for example by enabling combined schools to be identified separately (see box, right, showing that Petrova’s sample seriously underestimated the number of small secondary schools whether or not combined). This issue is less of a problem with primary schools where many small schools would be of similar size as the combined schools, and the latter make up a smaller proportion of the total number of schools. Of the 7,675 primary schools in 2009, 1,261 or 19.6% were primary sections of combined schools, while the secondary school sections of the same schools made up 46.7% of the total 2,700 schools classified as either secondary or combined primary and secondary.2
To conclude, the secondary sections of the combined schools are probably smaller on average than schools offering only Years 7 to 12. Furthermore, many combined schools would be in rural and remote areas throughout Australia, especially in states and territories with a large rural sector. Because a much larger proportion is made up of combined schools in the secondary school sample, and these are likely to differ from the average school catering for secondary level only, the nature of the sample of teachers who were approached, and who responded, becomes an issue.3
Teachers’ Qualifications and Demographics
Table 19 shows teachers’ educational qualifications for each age group defined in the survey, and by gender.4
Secondary school music teachers are much more highly qualified than their primary school counterparts — undoubtedly a genuine finding. Almost 89% were defined as having achieved high musical attainment compared with 48% of primary music teachers. Nine percent were moderately qualified and the absolute number of secondary music teachers with low qualifications was as low as three in the survey (2%), compared with 29% of primary teachers.
Nineteen of the 141 teachers in the secondary school sample were under 30 years old (13.5%). At the other end of the range 36 were 50 years and older (25.5%). The two mid-range age groups (30-39 and 40-49) both accounted for 30.5% of the total. This distribution differed from the primary school sample except that both had a low count of under-30s. Primary school music teachers were noticeably older with 31% 40-49 year-olds and 37% being 50 and over (Table 5 in Primary School Music Teaching).5
The secondary school sample also had a much higher proportion of males (40% compared with only 18% in the primary school survey). The female majority were less highly qualified than the males (84.5% as against 94.7%, but both genders were much better qualified at secondary level than in primary schools). The major difference in qualifications, as noted above, was that almost nine out of ten secondary school music teachers were highly qualified compared with less than half of their primary school colleagues.
The survey results are comparable with official teaching workforce statistics (none of which refer to music teachers as such, since specific published statistics of these don’t exist). Official statistics of full-time-equivalent (FTE) teaching staff are shown in the right-hand box. The percentages are reasonably comparable with the findings for primary and secondary music teachers, respectively.6
Prior and Current Musical Activities
Almost 91% of all secondary music teachers who were rated as highly qualified had chosen music when they attended secondary school themselves (Table 20). There was probably no statistically significant difference between secondary school teachers with different levels of musical attainment, given the small samples of teachers with less than high qualifications to teach. People with high qualifications, however, were more likely to have chosen music at every year of secondary school (52% of all these teachers). Relatively more persons with moderate qualifications had attended music classes in Year 12 only. The two last categories identified in Table 20 comprised a total 31% of both the high and moderate groups, but highly qualified teachers were more likely to have done music for two or more years including Year 12, and those with moderate (and the small number of low) qualifications were more likely to have done one year or more excluding Year 12.
These results and the primary school sample (Table 10) have some similarities. Primary school music teachers were also more likely to have taken music subjects every year from 7 to 12 — while the biggest group of primary teachers had taken one or more years of music excluding Year 12, but that percentage was smallest for those with high qualifications.
Overall, relatively more secondary teachers had taken any music subjects (90%) than among primary teachers (79%), and relatively more highly qualified secondary teachers had completed every year when they attended secondary school as students (28% of primary, 52% of secondary teachers).
Secondary music teachers played a somewhat different range from their primary school colleagues (Table 21). All played an instrument and/or sang, compared with 91.5% of primary teachers. As many as 78.7% of all secondary music teachers played keyboard, compared with 74.8% of primary music teachers (Table 11).
Comparable findings were: string instruments 62.4% of secondary, 54.3% of primary teachers; brass/woodwind 63.1% and 52.1%, percussion 18.4% and 13.6%. The only group where participation was higher among primary teachers was singing: 60.3% among secondary teachers, 70.9% among primary teachers.7
Some details on the five major musical activity groups follow:
- Of the total 111 observations on keyboard playing (79% of the total sample of secondary teachers), the piano figures in all but six (electronic keyboard only: 5; organ only: 1), that is, 94.5%. Thirty-three of the 111 played electronic keyboard (30%), 12 played organ (11% — Petrova Table 10.72). Among primary music teachers, 75% played keyboard, and 93% of these played the piano.
- String instruments were played by 88 secondary teachers (62% of the total sample). Three-quarters of those who played any string instrument played guitar, 32% violin, 15% double bass, 14% cello, and 10% cello (Table 10.73). In the primary school survey, 54% played a string instrument. That survey was even more dominated by the guitar (89% of those playing any string instrument). The only other instrument with any significant following was the violin (15%). Among secondary music teachers, in other words, there was a significant component who play orchestral and ensemble type strings.
- Eighty-nine secondary school teachers played brass or woodwind (63%). It was the most diverse of all groups. Of those who played any of these instruments, 38% played clarinet, 35% flute, 30% trumpet, 24% trombone, 12% saxophones, and 11% french horn. Other instruments scoring between three and seven observations included euphonium, recorder, tuba and oboe (Table 10.74). Brass/woodwind was also the most diverse in the primary school sample, where 51% played one or more of these instruments. The most common played there were flute, clarinet, recorder, trumpet, and saxophone. As with strings, orchestral instruments were more prevalent among secondary than primary teachers.
- Percussion was played by a minority only (Table 10.75): 26 of the sample of 141 secondary music teachers (18%). While this exceeded the participation rate of primary teachers (13%), the latter were divided into two non-overlapping groups of “conventional” and “African” percussion. In contrast, drum kits and similar accounted for 20 of the 26 secondary teacher observations (77%), with much less evidence of African instruments. Unconventional instruments numbered three, with one observation each — djembe, gamelan and marimba.
- There were 85 observations of vocal activity (60% of secondary teachers). Most sang only in choirs (49%), a minority sang solo only (9%), while 40% did both. The participation rate was higher among primary music teachers (71%), of whom 57% sang in choirs only, 11% sang solo only, and 32% did both8 (Petrova Table 10.76).
Teaching and Training Experience
Table 22 shows that almost half (47.5%) of secondary school music teachers had been teaching for 16 years or more, that is, since about 1992 from the vantage point of the 2009 survey.9. The other groups (one to five years ago, 6-10 and 11-15) may not be statistically different in view of the small sample. They each average 17.5%.
Chart 7 shows related information in terms of the estimated decade in which initial secondary teacher training took place. In the perspective of 2009, when the surveys were conducted, 23% of teachers trained in the past nine years since 2000, about 30% in each of the two previous decades (eighties and nineties), and about 17% of the total number of secondary teachers before 1980. It is derived from Petrova’s thesis relating to the period when secondary teachers undertook their initial training, from which Chart 7 was constructed. The complication was that some observations about initial training had to be allocated at midpoints within a decade, because the initial period of training might straddle adjacent decades. The upper quartile (1999) was estimated backwards from the 2000-08 period to remove bias resulting from this.
Medians and quartiles may be used to indicate when 25%, 50%, and 75% of the current teacher numbers started training. Petrova’s survey analysis suggests that 25% had begun their initial tertiary education since 1999 (“10 years ago”), and half had started since about 1991 (“18 years ago”). At the other end of the distribution, 25% of the current teacher population started training in 1982 or before (“27 years ago” or more).
Teacher Confidence and Related Perceptions
Confidence, and the related perceptions of whether teachers feel challenged and consider particular features adequate, are essential components of Irina Petrova’s research. Above all, she nominates the level of musical attainment (formal professional qualifications in music) as crucial. It should not be forgotten that even though the level of qualifications is much higher in secondary school music than in the primary sector, the survey still revealed that more than one in 10 teachers were not highly qualified (Table 19), not to mention that one in three secondary schools (including the secondary department of combined schools) have no classroom music. It is to Petrova’s great credit that these facts are revealed for all to see.
The survey asked separately for each year of secondary school how confident teachers felt about their teaching. The question was also asked about teaching for tertiary entrance examinations at the end of Year 12, and music extension and similar courses. The general impression from Chart 8 is that teachers are highly confident to teach years 7 to 10, and while slightly less confident about years 11 and 12 confidence remains high. Highly confident teachers are also quite confident about teaching for tertiary entry and extensions. The responses, however, vary more at these high teaching levels than for teaching years 7 to 10.10
Petrova notes (p 332): Qualification is crucial in making teachers confident in teaching music to every year of secondary school. We might add that it is also very important if Australia is going to keep improving the quality of future music teachers (and musicians generally) through maximising students’ chances to pass their entrance exams to higher education.
Confidence varies with age as well as with the level of qualifications (Chart 9). The youngest age group of secondary teachers is less confident on average but still reasonably confident in teaching senior secondary school students. They are significantly less confident in preparing Year 12 students for entrance exams and other extensions. The 30-39 year-olds were the most confident of the four age groups.11
The confidence patterns of male and female secondary music teachers are not very different as shown by the left-hand box. Males appear to be a little more confident than females about teaching Year 12 tertiary entry exams and extensions, but all are reasonably confident though not as much as they are about teaching normal curricula. The slight decline in confidence at years 11 and 12 apply to both genders.
Irina Petrova provides considerable detail on the challenges facing teachers at each level of secondary school (pp 336-361). A summary of average scores for each year is appropriate, and a visit is recommended to this valuable part of her thesis for further detail by level of qualification, sex and age. The survey form12 provided different questions for each pair of years (7-8, 9-10, and 11-12).
Years 7 and 8: Petrova inquired about the challenges of teaching the following contents (seven indicators): teaching (1) concepts of music, (2) composing, (3) performing and (4) listening; (5) planning lessons; and making suggestions about (6) performing and (7) listening repertoire. — Teachers felt these were not a major challenge (scores on scale of 7 between 2.29 and 3.02). (Petrova Table 10.81)
Years 9 and 10: The inquiry at this level included 16 criteria to be rated as challenges: (1) range of repertoire, (2) student compositions, (3) repertoire characteristic of additional topics studies, (4) improvising, (5) discussing capabilities of instruments and voices, (6) interpreting different musical notation styles, (7) using different types of performance technologies, (8) improvising, arranging and composing using various sound sources and movement activities, (9) using computer and other technologies to create and notate compositions, (10) notating compositions appropriate for selected music, (11) develop portfolio of compositional work, (12) analysing and discussing a range of repertoire and (13) how composers have used concepts of music in their work, and (14) reading and interpreting musical scores, (15) developing aural discrimination skills, and (16) sight-singing. — Despite the greater complexity of these items, teachers again didn’t feel greatly challenged: the average scores ranged from 2.29 to 3.37. (Table 10.84)
Years 11 and 12: There were five criteria of teaching performing (average scores 2.33 to 3.18), five of teaching composition (2.70 to 3.32), five of teaching musicology (2.34 to 2.95), and four of teaching aural activities (average scores 2.47 to 2.80). (Tables 10.87, 10.90, 10.90 and 10.93)
The ability of secondary school music teachers to remain fairly unchallenged by these tasks irrespective of the level taught supports the general impression from Petrova’s research that these teachers are generally highly skilled. This is a great boon for school music education, especially in these challenging times.
Areas Needing Improvement
The final three charts provide an opportunity to compare three states judged to have just (barely!) sufficient information through the small samples that resulted for the analysis of secondary schools. There were 48 observations for NSW but only 26 for Victoria and 17 for Queensland. The samples were considered too small for South Australia and Western Australia to yield meaningful comparative results.
The longer the bar on Chart 10, the more improvement is needed in the eyes of those completing the survey. There is reasonable agreement that program assessment and development is most lacking with average scores at around the “midpoint” of 4. Planning music programs and lessons, and implementing the music program, also hover around the midpoint, while levels are somewhat lower (less need for improvement) for the development of musicological knowledge and musical skills.
Queensland seemed to be in a particularly good position on the two latter criteria. Using our crude rating model (first position 3, second 2, and third 1 since there are only three states to compare), Queensland scores three firsts, a second and a third position (total score 12, with no added kudos for being particularly far ahead on musicological and musical skills development), NSW a first, three seconds and a third (total 10), and Victoria a first, a second and three thirds (total 8).
The scale on Chart 11 goes in the opposite direction: the favourable readings of sufficiency are the tallest bars. Again, we compare only the three largest states. Queensland again stands out.
Of the five variables on Chart 11, “meets curriculum demand” gets the highest average ratings, above the midpoint of 4. The average for Australia which includes all findings including those for the smaller states and territories (dark bar to the right in each set) is almost as high for “combination of specialist teachers” and is right on the midpoint for “time for music in timetable”. The score is lower for “qualified support staff” and “facilities for teaching music”.
Our crude ranking score gives Queensland three firsts and two seconds (one of which was .01 below the NSW score). NSW gets two firsts, one second and two thirds, Victoria two seconds and three thirds. Total scores: Queensland 13, NSW 10, Victoria 7 which is the same rank order as for Chart 10.
Chart 12 compares teaching resources in terms of sufficiency. The average for Australia (dark bars) is highest for traditional instruments and books and written resources (each around 4.70). The average is also above 4 for audio recordings and electronic instruments, marginally above 4 for computer software, and 3.86 for video recordings. These scores are generally higher than for the variables included in Chart 11.
The rankings of the three states were more consistently in favour of Queensland and against NSW than on the other charts. Queensland scores five firsts and a second to achieve 17 points (the maximum here is 18). Victoria gets one first, four seconds and one third to score 12, and NSW has one second and five thirds to score 7, one above the minimum possible.
Adequacy of training is the final topic to cover, and can be dealt with briefly. The findings for the small group of three teachers with low qualifications have been ignored as statistically unreliable. Petrova’s thesis has more indicators but these will provide the idea.
Pre-service teacher training was considered almost adequate. It was rated an average of 3.97 by the highly qualified teachers who dominate the secondary school sample, and 3.38 (somewhat inadequate) by the smaller sample of moderately qualified teachers. The overall average for adequacy was 3.89. (Petrova p 364)
In-service training was rated more harshly by both sections, The average for highly qualified secondary school teachers was 3.06, and for the moderately qualified teachers as low as 2.17. Overall average 3.01, inadequate (p 370).
Chart 23, finally, is based on Petrova’s Table 10.114 (p 372) and concerns the benefits of professional development workshops for secondary school teachers. These workshops were reasonably highly favoured for their benefits with an average score of between 4.37 and 4.79 for the highly qualified teachers depending on the criterion in question, and a score of between 4.00 and 4.64 for the smaller sample of moderately qualified ones.
By sheer chance, finalising the three reviews of Irina Petrova’s thesis on school music education for the knowledge base happened to coincide, literally within hours, with the Australian Minister for the Arts Simon Crean’s launch, on 13 March 2013, of Creative Australia, the national cultural policy taking over from “Creative Nation”, introduced by then Prime Minister Paul Keating in 1994.
The new policy for the first time introduces the arts into the National Curriculum. In view of the parlous state of classroom music, especially at primary level, the following quotes from the policy document are relevant (italics added):
“Including the arts in the Australian curriculum is an important step in building this creative capacity. For the first time, all Australian school children will be guaranteed an arts education. The importance of this cannot be underestimated, and its impact should be measured over the life of this policy as a new generation makes career choices by the end of the decade.” (p 41)
“The Australian Curriculum: The Arts in schools policy across Australia follows agreement between the Commonwealth and state governments to develop a national curriculum and will see students develop creative skills through access to music, media arts, dance, drama, and visual arts. The arts curriculum complements the funding of more than $14 billion provided as part of the Building the Education Revolution — Primary Schools for the 21st Century Program. This funding was provided across Australia for the construction of primary school infrastructure, including libraries and multi-purpose halls and performance spaces.” (p 47)
“The growth and stability of the cultural economy depends on a strong continuum, beginning with arts education for all in schools through the Australia Curriculum: the Arts, and continuing with appropriate tertiary and vocational education and elite training, supported by opportunities to make the jump from education to professional practice.” (p 71)
“”The Curriculum will ensure that every student, from Foundation to the end of primary school, will study the arts in a rigorous and sequential process.” Also, from the first year of high school, students will have an opportunity to experience some arts subjects in greater depth and to specialise in one or more arts subjects. The Curriculum will enable students to study the arts across five subjects — dance, drama, media arts, music and visual arts — and allow them to explore the relationship and interaction between artforms.” (p 78)
After the policy speech at the National Press Club in Canberra, one questioner commented that there might be a long way to go before the arts in schools program could be realised, and Mr Crean recognised that this might be the case. However, he stressed that the policy had been agreed between the Australian government and the state governments prior to the launch of the national cultural policy, and advocated a bipartisan approach in the interest of the nation’s long-term development.
Given the timing of the national policy launch, Irina Petrova’s thesis is also very well-timed, including her demonstration of the unsatisfactory state of primary school music education and the impact this has on the quality of the education in secondary schools despite the better quality of the teaching staff there. Her research makes it clear how big the challenge is, but it also provides a tool for helping to persuade the authorities in the educational and cultural sectors that this important part of the arts spectrum presents a major stumbling block for the development of the new cultural policy within a reasonable period of time — unless such a major weakness is given top priority and tackled decisively.
Hans Hoegh-Guldberg. Entered 13 March 2013.
- The content list is simpler than the description of primary school music mainly because the sample of secondary schools was smaller. For example, there was no data to match Tables 2 to 4 in Primary School Music Teaching, showing the number of government, Catholic and independent schools in each state and territory, and whether these employed specialist music teachers.↩︎
- Comparing the size distribution of primary schools in the same manner as is illustrated in the left-hand box for secondary schools, some bias exists towards large schools but not to the same extent. The bottom category of schools with 1-100 students (0-99 according to Petrova) comprised 14% of her total sample but 28% according to the ABS (2,158 of 7,675 primary schools). Schools with 101-300 students contributed 24.8% of the Petrova sample but 36.1% of total schools. There were considerably more schools with over 300 students in the sample (61.6%) than according to the ABS (35.8%). So the primary school sample is less skewed towards larger schools than the secondary school sample which contains a very low proportion of small schools, but still quite skewed.↩︎
- This section was included in the main text because the issue is too important to leave in a footnote. Furthermore, Petrova’s thesis does not specify as far as can be ascertained by a search for the words “combined schools” that she has addressed it. The results of the search were confined to the descriptions of the primary and secondary school samples following pages 241 and 315, where she doesn’t offer an explanation. Nowhere does she attempt to explore the specific character of combined schools, or for that matter whether or not a specific combined school has school music at both levels. How many, for example, might offer music at secondary level, and if so, give access to specially interested students from the primary section of the school? There is a host of issues that might be specifically addressed in these combined primary and secondary schools.↩︎
- Qualifications are defined in Petrova’s 2012 thesis, pp 247-248, as follows: High: Musical Degree or Diploma, Bachelor’s Degree with a music specialty, Master’s Degree in Music or Music Education. Moderate: Bachelor’s Degree with no music but supplemented by Grade 5 or higher in musical instrument playing, or completion of a Diploma of Associate in Music in Australia. Low: Bachelor’s Degree with no music and Grade 4 or lower in musical instrument playing, or no formal music education.↩︎
- Where it is clear that the reference is to primary teachers in the rest of this article, table numbers below 18 belong in Primary School Music Teaching.↩︎
- A study by the Australian Council for Educational Research (ACER) by Paul Weldon, Glen Rowley and Phillip McKenzie, Profile of Teachers in Selected Curriculum Areas, November 2011, pp 73-74, finds the male ratio to be similar: 20% of total staff in primary and 43% in secondary schools in 2010. The age distribution of Australian primary teachers was as follows: up to 35 years 28.7%, 36-50 years 40.3%, and over 50 years 33.4% (average age 43.2 years). The equivalent figures for all secondary teachers were 25.2%, 41.4%, and 34.7% (average age 44.1 years). The Petrova survey proportion of primary music teachers aged 50+ was 37.2%, considerably above the average for all teachers (Table 6). On the other hand, the official statistics relatively had many more teachers in the oldest age group than the 25.5% that are shown in Table 19.↩︎
- This may be associated with choirs attracting predominantly female members, which make up a larger percentage of primary school teachers.↩︎
- There was another vocal activity: individual tuition, practised by six (7%). One teacher did nothing else. There were also five mentions of individual tuition among primary teachers (less than 3% of teachers undertaking vocal activities).↩︎
- Table 5 showed that the proportion of primary teachers having taught music for 16 years or more was a slightly lower 43%, despite the age distribution of these teachers being tilted towards the 40-49 and 50+ groups↩︎
- Petrova discusses these matters in detail (pp 331-335). The variance is very low (< 1) for both highly and moderately qualified teachers for years 7 to 10; slightly higher but still low for teaching years 11 and 12. The variance is much higher, especially for the smaller sample of moderately qualified teachers, for the additional Year 12 courses — indicating that some of these teachers are confident and some are not, causing a wide spread in responses.↩︎
- By age, the variance was the lowest for the 30-39 year group but < 1 for all age groups up to Year 10. The variance then increases to between 1 and 2 for the three older groups but to nearly 3 for the 20-29 group. The variance is much higher measured against the responses to teaching extensions to Year 12 students &mash; between 4 and 5 for all groups except for reasons unknown staying below 2 for the 40-49 group (Petrova Table 10.79, p 334).↩︎
- See Petrova pp 1114-1129.↩︎