@article{VMUMM_2010_3_a6,
     author = {P. V. Nalivaǐko},
     title = {Cycle contraction in oriented graphs},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {36--38},
     year = {2010},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2010_3_a6/}
}