Francesc Rosselló Gabriel Valiente Analysis of Metabolic Pathways by Graph Transformation. 70-82 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3256&spage=70 2004 conf/gg/2004 ICGT db/conf/gg/icgt2004.html#RosselloV04