Não informado. (1946). Iowa farm science. Iowa State University of Science and Technology, Cooperative Extension Service.
Chicago-referens (17:e uppl.)Não informado. Iowa Farm Science. Ames, Iowa: Iowa State University of Science and Technology, Cooperative Extension Service, 1946.
MLA-referens (8:e uppl.)Não informado. Iowa Farm Science. Iowa State University of Science and Technology, Cooperative Extension Service, 1946.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.