Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X Articles in Press 2011 06 28 On the stability of generalized derivations on Banach algebras en Ansari-Piri Esmaeil University of Guilan anjidani ehsan university of Guilan 2011 05 28 Hyers-Ulam-Rassias stability generalized derivation bounded central approximate identity faithful Banach algebra