Não informado. (1946). Iowa farm science. Iowa State University of Science and Technology, Cooperative Extension Service.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Iowa Farm Science. Ames, Iowa: Iowa State University of Science and Technology, Cooperative Extension Service, 1946.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Iowa Farm Science. Iowa State University of Science and Technology, Cooperative Extension Service, 1946.
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