1. Degrees of unsolvability of constructible sets of integers;Boolos;J. Symbolic Logic,1968
2. A recursion-theoretic characterization of the ramified analytical hierarchy;Boyd;Trans. Am. Math. Soc.,1969
3. Minimal degrees and the jump operator;Cooper;J. Symbolic Logic,1973
4. An annotated bibiliography for the structure of the degrees below 0’ with special reference to that of the recursively enumerable degrees;Recursive Function Theory Newsl.,1974
5. The Undecidable,1965