@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/