Não informado. (1973). Illinois school research and development. Illinois Association for Supervision and Curriculum Development.
Citação do estilo Chicago (17ª ed.)Não informado. Illinois School Research and Development. Nottingham, Inglaterra: Illinois Association for Supervision and Curriculum Development, 1973.
Citação MLA (8ª ed.)Não informado. Illinois School Research and Development. Illinois Association for Supervision and Curriculum Development, 1973.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.