00356nam a2200121Ia 4500082001700000100002100017245005700038260004800095300002600143490005500169500000500224700000500229  a514bC678.CG  aCohan, Daniel E.  aCombinatorial group theory; a topological approachb  aCambridgebCambridge University Pressc1989  ax, 310p. Index, Bibl.  aLondon Mathematical Society student textsv no. 14  a  a