Anuj Dawar David Richerby Benjamin Rossman Choiceless polynomial time, counting and the Cai-Fürer-Immerman graphs. 31-50 2008 152 Ann. Pure Appl. Logic 1-3 http://dx.doi.org/10.1016/j.apal.2007.11.011 db/journals/apal/apal152.html#DawarRR08