Iowa State College. Agricultural Extension Dept & Iowa State College. Agricultural Extension Dept. Schools Section. (1912). School circular. Dept. of Agricultural Extension, Schools Section.
Chicago-viite (17. p.)Iowa State College. Agricultural Extension Dept ja Iowa State College. Agricultural Extension Dept. Schools Section. School Circular. Ames, Iowa: Dept. of Agricultural Extension, Schools Section, 1912.
MLA-viite (8. p.)Iowa State College. Agricultural Extension Dept ja Iowa State College. Agricultural Extension Dept. Schools Section. School Circular. Dept. of Agricultural Extension, Schools Section, 1912.
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