@article{SEMR_2005_2_a14,
     author = {O. V. Borodin and A. O. Ivanova},
     title = {An oriented $7$-colouring of planar graphs with girth at least~$7$},
     journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a},
     pages = {222--229},
     publisher = {mathdoc},
     volume = {2},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SEMR_2005_2_a14/}
}