Não informado. (1938). Bimonthly Bulletin of the North Dakota Agricultural Experiment Station. North Dakota Agricultural Experiment Station.
Chicago-referens (17:e uppl.)Não informado. Bimonthly Bulletin of the North Dakota Agricultural Experiment Station. Fargo, ND: North Dakota Agricultural Experiment Station, 1938.
MLA-referens (8:e uppl.)Não informado. Bimonthly Bulletin of the North Dakota Agricultural Experiment Station. North Dakota Agricultural Experiment Station, 1938.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.