Patrick Doherty Witold Lukaszewicz Andrzej Skowron Andrzej Szalas Knowledge Representation Techniques - A Rough Set Approach 202 2006 3-320 Springer Studies in Fuzziness and Soft Computing http://dx.doi.org/10.1007/3-540-33519-6 978-3-540-33518-4 db/series/sfsc/index.html#DohertyLSS06