Dirk Pattinson Lutz Schröder Beyond Rank 1: Algebraic Semantics and Finite Models for Coalgebraic Logics. 66-80 2008 FoSSaCS http://dx.doi.org/10.1007/978-3-540-78499-9_6 conf/fossacs/2008 db/conf/fossacs/fossacs2008.html#PattinsonS08