Gwaiz, S. A., & Peak, P. (1979). An analysis of approaches to teaching the differential in elementary calculus. Indiana University, Faculty of the Graduate School.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Gwaiz, Saleh Abdulrahman, و Philip Peak. An Analysis of Approaches to Teaching the Differential in Elementary Calculus. Indiana: Indiana University, Faculty of the Graduate School, 1979.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Gwaiz, Saleh Abdulrahman, و Philip Peak. An Analysis of Approaches to Teaching the Differential in Elementary Calculus. Indiana University, Faculty of the Graduate School, 1979.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.