1. Certain polynomial identities and commutativity of rings;M. Ashraf;Math. Slovaca,2000
2. On some commutativity theorems of Herstein;H. Bell;Arch. Math. (Basel),1973
3. A note on commutativity of rings;R. Gupta;Math. Student,1971
4. Some polynomial identities and commutativity of s-unital rings;Y. Hirano;Math. J. Okayama Univ,1982
5. Two remarks on the commutativity of rings;I. Herstein;Canad. J. Math,1955