1. La série de Poincaré-Betti d'une algèbre graduée de type fini à une relation est rationelle;Backelin;C. R. Acad. Sci. Paris Ser. A,1978
2. On universal derivations;Bergman;J. Algebra,1975
3. Universal derivations and universal ring constructions;Bergman;Pacific J. Math.,1978
4. Free Rings and Their Relations;Cohn,1971
5. Idealizers in Free Algebras;Dicks,1974