On the Paper by A. Najati and S.-M. Jung: The Hyers-Ulam Stability of Approximately Quadratic Mapping on Restricted Domains

Cauchy-Jensen additive mappings in quasi-Banach algebras and its applications

“…Gȃvruta [7] generalized the Rassias' result. The stability problems of several functional equations have been extensively investigated by a number of authors and there are many interesting results concerning this problem (see [5,6], [9,10], [12]- [19], [21]- [23], [28]- [30]). …”