@article{ZNSL_1979_88_a16,
     author = {P. Yu. Suvorov},
     title = {Representation of proof s' by coloured graphs and {Hadwiger} hypothesis},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {209--217},
     year = {1979},
     volume = {88},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1979_88_a16/}
}