| Author | Popularity |
| Belgium. Ministerie van Nationale Opvoeding en Nederlandse Cultuur |
8 |
| Belgium. Ministère de l'éducation nationale et de la culture française |
6 |
| International Conference on Education, 37th, Geneva, 1979 |
3 |
| International Conference on Education, 38th, Geneva, 1981 |
3 |
| Belgium. Direction générale de l'organisation des études |
2 |
| International Conference on Education, 34th, Geneva, 1973 |
1 |
| International Conference on Education, 36th, Geneva, 1977 |
1 |
