1. Model Theory;Chang,1973
2. Set Theory and the Continuum Hypothesis;Cohen,1966
3. Non-definability of certain semantic properties of programs;Demillo;Notre Dame J. Formal Logic,1975
4. Algorithmic procedures, generalized Turing algorithms, and elementary recursion theory;Friedman,1971
5. The complexity of explicit definitions;Friedman;Notices A.M.S.,1975