Huawen Liu Jigui Sun Huijie Zhang Lei Liu Extended Pawlak's Flow Graphs and Information Theory. 220-236 2009 5 Transactions on Computational Science http://dx.doi.org/10.1007/978-3-642-02097-1_12 journals/tcos/2009-5 db/journals/tcos/tcos5.html#LiuSZL09