@article{ZNSL_2014_427_a4,
     author = {G. V. Nenashev},
     title = {On {Heawood-type} problem for maps with tangencies},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {74--88},
     year = {2014},
     volume = {427},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2014_427_a4/}
}