Não informado. (1956). Instructional materials. National Education Association, Department of Audio Visual Instruction.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Instructional Materials. Washington: National Education Association, Department of Audio Visual Instruction, 1956.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Instructional Materials. National Education Association, Department of Audio Visual Instruction, 1956.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.