Genre
- Congresses 65 canlyniadau
- Case studies 12 canlyniadau
- Cross-cultural studies 8 canlyniadau
- Handbooks, manuals, etc 8 canlyniadau
- Biography 3 canlyniadau
- Curricula 1 canlyniadau
- Examinations, questions, etc 1 canlyniadau
- Longitudinal studies 1 canlyniadau
- Observations 1 canlyniadau
- Statistics 1 canlyniadau