1. A. A. Bovdi, ?On cross products of a semigroup and a ring,? Dokl. Akad. Nauk SSSR,137, No. 6, 307?313 (1961).
2. A. I. Mal'tsev, ?On the embedding of group algebras and algebras with divisors,? Dokl. Akad. Nauk SSSR,60, No. 9, 1499?1501 (1948).
3. N. Bourbaki, Commutative Algebra [Russian translation], Mir, Moscow (1971).
4. A. I. Mal'tsev, Algorithms and Recursive Functions [in Russian], Nauka, Moscow (1986).
5. Yu. L. Ershov and E. A. Palyutin, Mathematical Logic [in Russian], Nauka, Moscow (1987).