1. Non-Commutative Rings;Herstein,1968
2. Structure of Rings;Jacobson,1956
3. Der Typ der regulären Darstellung diskreter Gruppen;Kaniuth;Math. Ann.,1969
4. Group algebras in the large;Kaplansky;Tohoku Math. J.,1951
5. The structure of certain operator algebras;Kaplansky;Trans. Amer. Math. Soc.,1951