M. Kayed, und K. Shaalan. IEEE Transactions on Knowledge and Data Engineering18 (10):
1411--1428(2006)Member-Chia-Hui Chang and Member-Moheb Ramzy Girgis.
B. Bartsch-Spörl, M. Lenz, und A. Hübner. XPS-99: Knowledge-Based Systems - Survey and Future Directions,, Volume 1570 von Lecture Notes in Computer Science, Seite 67-89. Springer, (1999)