4Pawlak Z. Rough sets[J]. International Journal of Computer and Information Sciences, 1982, 11:341-356.
5Wille R. Restructuring lattice theory: an approach based on hierarchies of concepts[C]// Rival I (Ed.), Ordered Sets. Reidel, Dordrecht-Boston, 1982:445-470.
6Skowron A. Boolean reasoning for implication rules generation[C]//Komorowski J, Ras Z.(Eds.), Method- ologies for Intelligent Systems. Lecture Notes in Artificial Intelligence 689, Springer-Verlag, Berlin, 1993: 295-305.
7Skowron A, Rauszer C. The discernibility matrices and functions in information systems[C]// Slowinski R (Ed.), Intelligent Decision Support: Handbook of Applications and Advances of the Rough Sets Theory. Kluwer Academic Publishers, Boston, 1992:331-362.
8Beynon M. Reducts within the variable precision rough sets model: a further investigation[J]. European Journal of Operational Research, 2001, 134:592-605.
9Mi J-S, Wu W-Z, Zhang W-X. Approaches to knowledge reductions based on variable precision rough sets model[J]. Information Sciences, 2004, 159:255-272.
10Wu W-Z, Zhang W-X, Li H-Z, Mi J-S. Knowledge reduction in random information systems via Dempster- Shafer theory of evidence[J]. Information Sciences, 2005, 174(3-4): 143-164.