Rodolfo Castelló Rym Mili Ioannis G. Tollis An Algorithmic Framework for Visualizing Statecharts. 139-149 http://link.springer.de/link/service/series/0558/bibs/1984/19840139.htm 2000 conf/gd/2000 Graph Drawing db/conf/gd/gd2000.html#CastelloMT00