1. P.H.G. Aczel, M. Rathjen, Notes on constructive set theory, Report No. 40, Institut Mittag-Leffler, Royal Swedish Academy of Sciences, 2001.
2. Foundations of Constructive Analysis;Bishop,1967
3. Constructive Analysis;Bishop,1985
4. A constructive Morse theory of sets;Bridges,1987
5. Varieties of Constructive Mathematics;Bridges,1987