1. A. N. Degtev, ?Reducibility of partial recursive functions. I,? Sib. Mat. Zh.,16, No. 5, 970?988 (1975).
2. A. N. Degtev, ?Reducibility of partial recursive functions. II,? Sib. Mat. Zh.,17, No. 4, 765?774 (1977).
3. Yu. L. Ershov, Theory of Numerations [in Russian], Nauka, Moscow (1977).
4. A. N. Degtev, ?On m-degrees of simple sets,? Algebra Logika,11, No. 2, 130?139 (1972).
5. T. P. Cleave, ?Some properties of recursively unseparable sets,? Z. Math. Logik Grundl. Math.,16, No. 2, 187?200 (1970).