@article{VMUMM_1990_5_a8,
     author = {E. V. Shikin},
     title = {Parabolicity of embeddable and hyperbolicity of nonembeddable two-dimensional manifolds of negative curvature},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {42--45},
     publisher = {mathdoc},
     number = {5},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_5_a8/}
}