Não informado. (1919). University of Iowa Studies in Natural History. University of Iowa.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. University of Iowa Studies in Natural History. Iowa City, Iowa: University of Iowa, 1919.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. University of Iowa Studies in Natural History. University of Iowa, 1919.
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