Não informado. (1952). Elementary school science bulletin. National Science Teachers Association.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Elementary School Science Bulletin. Washington: National Science Teachers Association, 1952.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Elementary School Science Bulletin. National Science Teachers Association, 1952.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.