Eskandani, G. Z., and J. M. Rassias. “Approximation of General α-Cubic Functional equations in 2-Banach Spaces”. Ukrains’kyi Matematychnyi Zhurnal 68, no. 10 (October 25, 2016): 1430-1436. Accessed April 26, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1930.