John Micheal Rassias, Elumalai Sathya, and Mohan Arunkumar. “Stabilities of Mixed Type Quintic-Sextic Functional Equations in Various Normed Spaces”. Malaya Journal of Matematik, vol. 9, no. 01, Jan. 2021, pp. 217-43, https://www.malayajournal.org/index.php/mjm/article/view/1006.