M. Arunkumar, John M. Rassias, S. Murthy, and M. Arulselvan, “Stability of a 2 - Variable AC - Mixed Type Functional Equation in Paranormed Spaces: Direct and Fixed Point Methods”, Int. J. Math. And Appl., vol. 4, no. 4 (Special Issue), pp. 43–58, Dec. 2016.