1. On recursively saturated models of arithmetic;Barwise,1975
2. Foundations of Constructive Analysis;Bishop,1967
3. A simplification of the Bachmann method for generating large countable ordinals;Bridge;J. Symbolic Logic,1975
4. Normalfunktionen und konstruktive Systeme von Ordinalzahlen;Buchholz,1975
5. A formulation of the simple theory of types;Church;J. Symbolic Logic,1940