1. Centralizers in free associative algebras;Bergman, George M.;Trans. Amer. Math. Soc.,1969
2. Unsolvability of the word problem, and subalgebras of finitely presented Lie algebras;Bokut′, L. A.;Izv. Akad. Nauk SSSR Ser. Mat.,1972
3. Subalgebras of free associative algebras;Cohn, P. M.;Proc. London Math. Soc. (3),1964
4. London Mathematical Society Monographs;Cohn, P. M.,1985
5. Automorphisms of a free associative algebra of rank 2. I;Czerniakiewicz, Anastasia J.;Trans. Amer. Math. Soc.,1971