1. Which set existence axioms are needed to prove the separable Hahn-Banach theorem?
2. Functional Analysis in Weak Subsystems of Second Order Arithmetic. Ph. D. thesis Pennsylvania State University 1987.
3. Real and Complex Analysis. McGraw-Hill, New York 1966.
4. Subsystems of Z2 and reverse mathematics. Appendix to: G. Takeuti, Proof Theory, 2nd ed. North-Holland Publ. Comp., Amsterdam 1986, pp. 434–448.
5. Which set existence axioms are needed to prove the Cauchy/Peano theorem for ordinary differential equations?