1. A. Church, for a very thorough treatment of sentential, predicate, and higher-order logic
2. H. B. Curry—R. Feys, for a full and systematic account of combinatory logic
3. A.Fraenkel, for a detailed treatment of the theory of sets, with special stress on its fundamental concepts
4. F. Hausdorff and [2], for a concise but lucid account of the theory of sets, emphasising its applications in various domains of mathematics
5. A. Heyting, for intuitionistic logic and mathematics