@article{PDM_2013_4_a7,
     author = {Yu. L. Kostyuk},
     title = {The travelling salesman problem: improved lower bound in the branch-and-bound method},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {73--81},
     publisher = {mathdoc},
     number = {4},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2013_4_a7/}
}