Iowa State College. Agricultural Extension Dept & Iowa State College. Agricultural Extension Dept. Schools Section. (1912). School circular. Dept. of Agricultural Extension, Schools Section.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Iowa State College. Agricultural Extension Dept و Iowa State College. Agricultural Extension Dept. Schools Section. School Circular. Ames, Iowa: Dept. of Agricultural Extension, Schools Section, 1912.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Iowa State College. Agricultural Extension Dept و Iowa State College. Agricultural Extension Dept. Schools Section. School Circular. Dept. of Agricultural Extension, Schools Section, 1912.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.