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-viite (17. p.)Iowa State College. Agricultural Experiment Station ja Iowa State College. Agricultural Extension Station. Bulletin P. Ames, Iowa: Agricultural Experiment Station--Agricultural Extension Service, Iowa State College, 1939.
MLA-viite (8. p.)Iowa State College. Agricultural Experiment Station ja Iowa State College. Agricultural Extension Station. Bulletin P. Agricultural Experiment Station--Agricultural Extension Service, Iowa State College, 1939.
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