Iowa. Bureau of Labor Statistics. (1920). The State Free Employment Bureau: Co-operating as the State-Federal Employment Service ; including farm wage data for biennium ending June 30, 1920. State of Iowa.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Iowa. Bureau of Labor Statistics. The State Free Employment Bureau: Co-operating as the State-Federal Employment Service ; Including Farm Wage Data for Biennium Ending June 30, 1920. Des Moines: State of Iowa, 1920.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Iowa. Bureau of Labor Statistics. The State Free Employment Bureau: Co-operating as the State-Federal Employment Service ; Including Farm Wage Data for Biennium Ending June 30, 1920. State of Iowa, 1920.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.