Não informado. (1973). Illinois school research and development. Illinois Association for Supervision and Curriculum Development.
Chicago-referens (17:e uppl.)Não informado. Illinois School Research and Development. Nottingham, Inglaterra: Illinois Association for Supervision and Curriculum Development, 1973.
MLA-referens (8:e uppl.)Não informado. Illinois School Research and Development. Illinois Association for Supervision and Curriculum Development, 1973.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.