1. Avigad, J., Feferman, S.: Gödel’s functional interpretation. In: Buss, S. (ed.) Handbook of Proof Theory. Elsevier, Amsterdam (1998)
2. Bel’tyukov, A.: A machine description and the hierarchy of initial Grzegorczyk classes. J. Soviet Math (1982), Zap. Naucn. Sem. Leninigrad. Otdel. May. Inst. Steklov (LOMI) 88, 30–46 (1982)
3. Clote, P.: Computation models and function algebra. In: Griffor, E. (ed.) Handbook of Computability Theory. Elsevier, Amsterdam (1996)
4. Ehrenfeucht, A.: Polynomial functions with exponentiation are well ordered. Algebra Universalis 3, 261–262 (1973)
5. Esbelin, M.A., More, M.: Rudimentary relations and primitive recursion: A toolbox. Theoretical Computer Science 193, 129–148 (1998)