1. Birkhoff, G.: Lattice Theory. American Mathematical Society, Providence (1940)
2. Lecture Notes in Computer Science;J.W. Grzymala-Busse,1991
3. Grzymala-Busse, J.W.: LERS – A system for learning from examples based on rough sets. In: Slowinski, R. (ed.) Intelligent Decision Support. Handbook of Applications and Advances of the Rough Sets Theory, pp. 3–18. Kluwer Academic Publishers, Dordrecht (1992)
4. Grzymala-Busse, J.W.: Rough set strategies to data with missing attribute values. In: Workshop Notes, Foundations and New Directions of Data Mining, the 3rd International Conference on Data Mining, Melbourne, FL, USA, November 19-22, pp. 56–63 (2003)
5. Lecture Notes in Artificial Intelligence;J.W. Grzymala-Busse,2001