@article{02057405, title = {Combination of convergence groups.}, journal = {Geometry \& Topology}, volume = {7}, year = {2003}, pages = {933-963}, doi = {10.2140/gt.2003.7.933}, zbl = {1037.20042}, language = {en}, url = {http://dml.mathdoc.fr/item/02057405} }
Dahmani, François. Combination of convergence groups.. Geometry & Topology, Tome 7 (2003) pp. 933-963. doi : 10.2140/gt.2003.7.933. http://gdmltest.u-ga.fr/item/02057405/