Não informado. (1919). University of Iowa Studies in Natural History. University of Iowa.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. University of Iowa Studies in Natural History. Iowa City, Iowa: University of Iowa, 1919.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. University of Iowa Studies in Natural History. University of Iowa, 1919.
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