@article{IM_1985__79_143199,
     author = {Viktor Schroeder},
     title = {A splitting theorem for spaces of nonpositive curvature.},
     journal = {Inventiones mathematicae},
     pages = {323--328},
     publisher = {mathdoc},
     volume = {79},
     year = {1985},
     zbl = {0543.53036},
     url = {http://geodesic.mathdoc.fr/item/IM_1985__79_143199/}
}