@article{TDM_1998_2_a14,
     author = {V. N. Sachkov},
     title = {The reduction {operator.~I}},
     journal = {Trudy po diskretnoj matematike},
     pages = {282--295},
     publisher = {mathdoc},
     volume = {2},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TDM_1998_2_a14/}
}