@article{DM_1991_3_2_a8,
     author = {N. P. Khomenko and V. G. Leshchenko},
     title = {Planarity of coverings of graphs},
     journal = {Diskretnaya Matematika},
     pages = {103--113},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1991_3_2_a8/}
}