M. Arunkumar, P. Narasimman, E. Sathya, and N. Mahesh Kumar. “3 Dimensional Additive Quadratic Functional Equation”. Malaya Journal of Matematik 5, no. 01 (January 1, 2017): 72–103. Accessed November 23, 2024. https://www.malayajournal.org/index.php/mjm/article/view/581.