Qian Gao Fei Liu David Gilbert Monika Heiner David Tree A multiscale approach to modelling planar cell polarity in Drosophila wing using hierarchically coloured Petri nets. 209-218 2011 CMSB http://doi.acm.org/10.1145/2037509.2037538 conf/cmsb/2011 db/conf/cmsb/cmsb2011.html#GaoLGHT11