M. Eshaghi Gordji, S. Kaboli Gharetapeh, M. Bidkham, T. Karimi and M. Aghaei. (2011). Almost Homomorphisms Between Unital $C^*$-Algebras: A Fixed Point Approach. Analysis in Theory and Applications. 27 (4). 320-331. doi:10.1007/s10496-011-0320-3