@article{UZKU_2011_153_4_a2,
     author = {E. N. Sosov},
     title = {Relative $N$-radius of a~bounded subset of a~metric space},
     journal = {U\v{c}\"enye zapiski Kazanskogo universiteta. Seri\^a Fiziko-matemati\v{c}eskie nauki},
     pages = {28--36},
     year = {2011},
     volume = {153},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZKU_2011_153_4_a2/}
}