1. Differential polynomials and division algebras;Amitsur;Ann. of Math.,1954
2. Derivations in simple rings;Amitsur,1957
3. A ring primitive on the right but not on the left;Bergman,1964
4. Les T-anneaux et les anneaux à identités polynomials noethériens;Cauchon;Thèse,1977
5. Free Rings and Their Relations;Cohn,1971