Não informado. (1973). Illinois school research and development. Illinois Association for Supervision and Curriculum Development.
Chicago-Zitierstil (17. Ausg.)Não informado. Illinois School Research and Development. Nottingham, Inglaterra: Illinois Association for Supervision and Curriculum Development, 1973.
MLA-Zitierstil (8. Ausg.)Não informado. Illinois School Research and Development. Illinois Association for Supervision and Curriculum Development, 1973.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.