1. Hypersimple sets with retraceable complements;Degtev, A. N.;Algebra i Logika,1971
2. On the degrees of universal regressive isols;Ellentuck, Erik;Math. Scand.,1973
3. Recursive density types. II;Gonshor, H.;Trans. Amer. Math. Soc.,1969
4. Classes of recursively enumerable sets and degrees of unsolvability;Martin, Donald A.;Z. Math. Logik Grundlagen Math.,1966
5. Trees and isols. I;McLaughlin, T. G.;Rocky Mountain J. Math.,1975