@article{INTG_1975_7_a14,
     author = {E. V. Shikin},
     title = {Isometric imbeddings in~$E^3$ of noncompact domains of nonpositive curvature},
     journal = {Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara},
     pages = {249--266},
     year = {1975},
     volume = {7},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTG_1975_7_a14/}
}