@article{DM_2009_21_4_a10,
     author = {D. S. Malyshev},
     title = {On the number of boundary classes in the 3-colouring problem},
     journal = {Diskretnaya Matematika},
     pages = {129--134},
     year = {2009},
     volume = {21},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_2009_21_4_a10/}
}