@article{GDZPPN002436965, title = {Ramified Coverings with Nonpositive Curvature.}, journal = {Mathematische Zeitschrift}, volume = {205}, year = {1990}, pages = {123-128}, zbl = {0694.53040}, url = {http://dml.mathdoc.fr/item/GDZPPN002436965} }
Schroeder, Viktor; Fornari, Susana. Ramified Coverings with Nonpositive Curvature.. Mathematische Zeitschrift, Tome 205 (1990) pp. 123-128. http://gdmltest.u-ga.fr/item/GDZPPN002436965/