@article{VMUMM_1989_6_a14,
     author = {I. A. Muzychuk},
     title = {Nonexistence of some twelfth-order $4$-critical graphs},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {58--60},
     year = {1989},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_6_a14/}
}