@article{DA_2010_17_2_a1,
     author = {O. V. Borodin},
     title = {Acyclic 4-colorability of planar graphs without 4- and 5-cycles},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {20--38},
     publisher = {mathdoc},
     volume = {17},
     number = {2},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_2010_17_2_a1/}
}