Sapp, G. (1941). Happy helpers. Florida curriculum laboratory, College of education, University of Florida and State dept. of education.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Sapp, Gertrude. Happy Helpers. Gainesville: Florida curriculum laboratory, College of education, University of Florida and State dept. of education, 1941.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Sapp, Gertrude. Happy Helpers. Florida curriculum laboratory, College of education, University of Florida and State dept. of education, 1941.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.