@conference {121, title = {Proof Graphs for Parameterised Boolean Equation Systems}, booktitle = {CONCUR 2013 {\textendash} Concurrency Theory}, series = {Lecture Notes in Computer Science}, volume = {8052}, year = {2013}, pages = {470-484}, publisher = {Springer}, organization = {Springer}, author = {Sjoerd Cranen and Bas Luttik and Tim A. C. Willemse} }