V. Nasiri, M. Arunkumar, E. Sathya, and T. Namachivayam. “Functional Inequalities for a Generalized Quadratic Functional Equation in Various Banach Spaces”. Malaya Journal of Matematik, vol. 9, no. 01, Jan. 2021, pp. 966-80, https://www.malayajournal.org/index.php/mjm/article/view/1205.