@article{SM_1972_18_1_a4,
     author = {\`E. R. Rozendorn},
     title = {The nonembeddability of complete $q$-metrics of negative curvature in a~class of weakly nonregular surfaces},
     journal = {Sbornik. Mathematics},
     pages = {83--92},
     publisher = {mathdoc},
     volume = {18},
     number = {1},
     year = {1972},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1972_18_1_a4/}
}