Não informado. (1956). Instructional materials. National Education Association, Department of Audio Visual Instruction.
Chicago-Zitierstil (17. Ausg.)Não informado. Instructional Materials. Washington: National Education Association, Department of Audio Visual Instruction, 1956.
MLA-Zitierstil (8. Ausg.)Não informado. Instructional Materials. National Education Association, Department of Audio Visual Instruction, 1956.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.