@article{DM_1992_4_1_a5,
     author = {O. V. Borodin},
     title = {A~structural theorem on planar graphs and its application to coloring},
     journal = {Diskretnaya Matematika},
     pages = {60--65},
     year = {1992},
     volume = {4},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1992_4_1_a5/}
}