Iowa State College. Agricultural Extension Dept. (1921). Agricultural extension bulletin. The Dept..
Lua i Stíl Chicago (17ú heag.)Iowa State College. Agricultural Extension Dept. Agricultural Extension Bulletin. Ames, Iowa: The Dept., 1921.
Lua MLA (8ú heag.)Iowa State College. Agricultural Extension Dept. Agricultural Extension Bulletin. The Dept., 1921.
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