1. Initial segments of the degrees of size ℵ1;Abraham;Israel J. Math.,1986
2. Independence results on the global structure of the Turing degrees;Groszek;Trans. Amer. Math. Soc.,1983
3. Set Theory: An Introduction to Independence Proofs;Kunen,1980
4. Degrees of Unsolvability;Sacks,1963
5. Biinterpretability and rigidity of hyperdegrees;Shore,2008