Iowa State College. Agricultural Experiment Station & Iowa State College. Agricultural Extension Station. (1939). Bulletin P. Agricultural Experiment Station--Agricultural Extension Service, Iowa State College.
Chicago-referens (17:e uppl.)Iowa State College. Agricultural Experiment Station och Iowa State College. Agricultural Extension Station. Bulletin P. Ames, Iowa: Agricultural Experiment Station--Agricultural Extension Service, Iowa State College, 1939.
MLA-referens (8:e uppl.)Iowa State College. Agricultural Experiment Station och Iowa State College. Agricultural Extension Station. Bulletin P. Agricultural Experiment Station--Agricultural Extension Service, Iowa State College, 1939.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.