1. An embedding of PI-rings;Amitsur,1952
2. On the semi-simplicity of group algebras;Amitsur;Michigan Math. J.,1959
3. Group rings of torsion free groups (in Russian);Bovdi;Sibirsk. Mat. Z̆.,1960
4. On the group ring;Connell;Canadian J. Math.,1963
5. Partially Ordered Algebraic Systems;Fuchs,1963