1. S. C. Kleene, Introduction to Metamathematics (Wolters-Noordhoff, 1952; IL, Moscow, 1957).
2. V. E. Plisko, “Absolute Realizability of Predicate Formulas,” Izvestiya Akad. Nauk SSSR, Matem. 47 (2), 315 (1983).
3. W. Ruitenburg, “Basic Predicate Calculus,” Notre Dame J. Formal Logic 39 (1), 18 (1998).
4. S. Salehi, “Primitive Recursive Realizability and Basic Arithmetic,” Bull. Symbol. Logic 7 (1), 147 (2001).