Não informado. (1926). Bulletin of the National Association of Secondary School Principals. National Association of Secondary School Principals.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Bulletin of the National Association of Secondary School Principals. Washington: National Association of Secondary School Principals, 1926.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Bulletin of the National Association of Secondary School Principals. National Association of Secondary School Principals, 1926.
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