Kečkić, J. D. (1970). A differential operator and its applications to partial differential equations and nonanalytic functions. Univerzitet, Elektrotehnički fakultet].
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Kečkić, Jovan D. A Differential Operator and Its Applications to Partial Differential Equations and Nonanalytic Functions. [Beograd: Univerzitet, Elektrotehnički fakultet], 1970.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Kečkić, Jovan D. A Differential Operator and Its Applications to Partial Differential Equations and Nonanalytic Functions. Univerzitet, Elektrotehnički fakultet], 1970.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.