@article{RM_1977_32_6_a14,
     author = {G. N. Kopylov and E. A. Timofeev},
     title = {Centers and radii of graphs},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {32},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1977_32_6_a14/}
}