Charles C. Sims Implementing the Baumslag-Cannonito-Miller Polycyclic Quotient Algorithm. 707-723 1990 9 J. Symb. Comput. 5/6 db/journals/jsc/jsc9.html#Sims90a http://dx.doi.org/10.1016/S0747-7171(08)80084-3