@article{MZM_1969_5_6_a8,
     author = {K. M. Belov},
     title = {Closed surfaces},
     journal = {Matemati\v{c}eskie zametki},
     pages = {719--721},
     publisher = {mathdoc},
     volume = {5},
     number = {6},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1969_5_6_a8/}
}