@article{CMH_1971__46_139481,
     author = {Esther Portnoy},
     title = {Toward a {Generalized} {Gauss-Bonnet} {Formula} for {Complete,} {Open} {Manifolds}},
     journal = {Commentarii mathematici Helvetici},
     pages = {324--344},
     year = {1971},
     volume = {46},
     zbl = {0223.53041},
     url = {http://geodesic.mathdoc.fr/item/CMH_1971__46_139481/}
}