Não informado. (1977). Core: Collected original resources in education. Carfax Publishing.
Chicago-Zitierstil (17. Ausg.)Não informado. Core: Collected Original Resources in Education. Oxford, Inglaterra: Carfax Publishing, 1977.
MLA-Zitierstil (8. Ausg.)Não informado. Core: Collected Original Resources in Education. Carfax Publishing, 1977.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.