1. D. Saks, Saturated Model Theory [Russian translation], Mir, Moscow (1976).
2. V. Harnik and M. Makkai, ?Applications of Vaught sentences and the covering theorem,? J. Symb. Logic,41, No. 1, 171?187 (1946).
3. Yu. L. Ershov, The Theory of Numerations [in Russian], Vol. 3, Novosibirsk Univ., Novosibirsk (1974).
4. H. Rogers, Jr., Theory of Recursive Functions and Effective Computability, McGraw-Hill (1967).
5. C. C. Chang and H. J. Keisler, Model Theory, Elsevier (1974).