1. Aczel, P.: Non-Well Founded Sets, Stanford. CSLI Lecture Notes, vol. 14 (1988)
2. Lecture Notes in Computer Science;P. Aczel,1989
3. Atzeni, P., Mecca, G., Meraildo, P.: To Weave the Web. In: International Conf. on Very Large Data Bases, VLDB 1997, pp. 206–215 (1997)
4. Electronic Notes in Theoretical Computer Science;A. Baltag,2000
5. Lecture Notes;J. Barwise,1996