1. Hyafil L., Rivest R.L., Constructing optimal binary decision trees is NP-complete, Information Processing Letters, Vol. 5, No. 1,May 1976, pp. 15–17.
2. Hong J., Mozetic I., Michalski R.S., AQ-15: Incremental Learning of Attribute-Based Descriptions from Examples, The Method and User's Guide, Report ISG 86-5, UIUCDCS-F-86-949, Dept of Computer Science, University of Illinois, Urbana, 1986.
3. Michalski R.S., Inferential Learning Theory: A Conceptual Framework for Characterizing Learning Processes, Report P91-13 MLI 91-6, Center for Artificial Intelligence, George Mason University, Fairfax, 1991.
4. Pawlak Z., Rough Sets, International Journal of Computer and Information Sciences, Vol. 11, No. 5, 1982, pp. 341–356.
5. Pawlak Z., Rough Sets, Theoretical Aspects of Reasoning about Data, Kluwer Academic Publishers, 1991.