Não informado. (1956). Instructional materials. National Education Association, Department of Audio Visual Instruction.
Chicago-viite (17. p.)Não informado. Instructional Materials. Washington: National Education Association, Department of Audio Visual Instruction, 1956.
MLA-viite (8. p.)Não informado. Instructional Materials. National Education Association, Department of Audio Visual Instruction, 1956.
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