1. Foundations of Constructive Mathematics;Beeson,1985
2. Grundlagen der Kombinatorischen Logik;Curry;Am. J. Math.,1930
3. A language and axioms for explicit mathematics;Feferman,1975
4. Constructive theories of functions and classes;Feferman,1979
5. On proving that 1 is an indecomposable projective in various free categories (manuscript);Freyd,1978