1. The non-derivability in intuitionistic formal systems of theorems on the continuity of effective operations;Beeson;J. Symbolic Logic,1975
2. The Unprovability of Consistency;Boolos,1979
3. Arithmetization of metamathematics in a general setting;Feferman;Fund. Math.,1960
4. Transfinite recursive progression of axiomatic theories;Feferman;J. Symbolic Logic,1962
5. Classically and intuitionistically provably recursive functions;Friedman,1973