Terry Caelli Serhiy Kosinov An Eigenspace Projection Clustering Method for Inexact Graph Matching. 515-519 2004 26 IEEE Trans. Pattern Anal. Mach. Intell. 4 http://csdl.computer.org/comp/trans/tp/2004/04/i0515abs.htm db/journals/pami/pami26.html#CaelliK04