1. Über eine bisher noch nicht benützte Erweiterung des finiten Stand-punktes;Gödel;Dialectica,1958
2. Transfinite induction and Bar induction of types 0 and one. and the role of continuity in intuitionistic analysis;Howard;JSL,1966
3. Natural deduction;Prawitz,1965
4. Some results for intuitionistic logic with second order quantification rules;Prawitz,1970
5. Mathematical Logic;Shoenfield,1967