1. H. Rogers, Theory of Recursive Functions and Effective Computability (McGraw Hill, N. Y., 1967; Mir, Moscow, 1972).
2. S. S. Marchenkov, “On a Class of Incomplete Sets,” Matem. Zametki 20(4), 473–478 (1976).
3. O. V. Belegradek, “On Algebraically Closed Groups,” Algebra i Logika 13(3), 239–255 (1974).
4. M. M. Arslanov and R. Sh.Omanadze, “Q-Degrees of n-c. e. Sets,” Illinois J. Math. 51(4), 1189–1206 (2007).
5. R. I. Soare, Recursively Enumerable Sets and Degrees (Heidelberg, Springer-Verlag, 1987; Kazan, Kazan Matem. Ob-vo, 2000).