Helfant, S. (1969). Training and motivating retail sales people. Independent Stores Division, National Retail Merchants Association.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Helfant, Seymour. Training and Motivating Retail Sales People. New York: Independent Stores Division, National Retail Merchants Association, 1969.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Helfant, Seymour. Training and Motivating Retail Sales People. Independent Stores Division, National Retail Merchants Association, 1969.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.