@article{TM_1980_152_a6,
     author = {M. D. Kovalev},
     title = {A~characteristic property of a~disc},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {124--137},
     publisher = {mathdoc},
     volume = {152},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1980_152_a6/}
}