@article{GDZPPN002327813, title = {Rigidity of Nonpositively Curved Graphmanifolds.}, journal = {Mathematische Annalen}, volume = {275}, year = {1986}, pages = {19-26}, zbl = {0591.53038}, url = {http://dml.mathdoc.fr/item/GDZPPN002327813} }
Schroeder, Viktor. Rigidity of Nonpositively Curved Graphmanifolds.. Mathematische Annalen, Tome 275 (1986) pp. 19-26. http://gdmltest.u-ga.fr/item/GDZPPN002327813/