@article{ZNSL_2012_406_a1,
     author = {D. V. Karpov},
     title = {Upper bound on  the number of edges of an almost planar bipartite graph},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {12--30},
     publisher = {mathdoc},
     volume = {406},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2012_406_a1/}
}