Não informado. (1971). Educational documentation and information. International Bureau of Education.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Educational Documentation and Information. Geneve, Suíça: International Bureau of Education, 1971.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Educational Documentation and Information. International Bureau of Education, 1971.
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