Hajo Broersma Fedor V. Fomin Jaroslav Nesetril Gerhard J. Woeginger More About Subcolorings. 187-203 2002 69 3 Computing http://www.link.springer.de/link/service/journals/00607/bibs/2069003/20690187.htm db/journals/computing/computing69.html#BroersmaFNW02