“…Since then, a large number of papers have been published in connection with various generalizations of Ulam's type stability theory or the Ulam-Hyers stability theory. For the advanced contribution on Ulam's type stability, we refer to [1-3, 6, 7, 10, 11, 13, 18, 19, 21, 22, 26, 27] and other stability results [12,17,24,25].…”