Daniel Král Pavel Nejedlý Group Coloring and List Group Coloring Are Pi<sub>2</sub>P-Complete (Extended Abstract). 274-286 http://dx.doi.org/10.1007/978-3-540-28629-5_19 2004 conf/mfcs/2004 MFCS db/conf/mfcs/mfcs2004.html#KralN04