1. K. A. Zhevlakov, A. M. Slin'ko, I. P. Shestakov, and A. I. Shirshov, Nearly Associative Rings [in Russian], Nauka, Moscow (1978).
2. S. V. Pchelintsev, ?Nilpotency of the associator ideal of a free finitely-generated (?1, 1)-ring,? Algebra Logika,14, No. 5, 543?571 (1975).
3. I. P. Shestakov, ?On a problem of Shirshov,? Algebra Logika,16, No. 2, 227?246 (1977).
4. V. T. Filippov, ?On chains of manifolds generated by free Mal'tsev and alternative algebras,? Dokl. Akad. Nauk SSSR,260, No. 5, 1082?1085 (1981).
5. I. R. Hentzel, ?The characterization of (?1, 1)-rings,? J. Algebra,30, Nos. 1?3, 236?258 (1974).