1. On stability of additive mappings;Gajda, Zbigniew;Internat. J. Math. Math. Sci.,1991
2. On the stability of the linear functional equation;Hyers, D. H.;Proc. Nat. Acad. Sci. U.S.A.,1941
3. On the stability of the linear mapping in Banach spaces;Rassias, Themistocles M.;Proc. Amer. Math. Soc.,1978
4. On a modified Hyers-Ulam sequence;Rassias, Themistocles M.;J. Math. Anal. Appl.,1991
5. Interscience Tracts in Pure and Applied Mathematics, no. 8;Ulam, S. M.,1960