@article{SEMR_2017_14_a60,
     author = {V. N. Stepanov},
     title = {A characteristic property of the ball},
     journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a},
     pages = {614--619},
     publisher = {mathdoc},
     volume = {14},
     year = {2017},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SEMR_2017_14_a60/}
}