@article{DM_1992_4_4_a6,
     author = {F. F. Dragan and K. F. Prisakar' and V. D. Chepoi},
     title = {The location problem on graphs and the {Helly} problem},
     journal = {Diskretnaya Matematika},
     pages = {67--73},
     year = {1992},
     volume = {4},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DM_1992_4_4_a6/}
}