@article{SEMR_2023_20_1_a18,
     author = {A. V. Kostin},
     title = {Problem of shadow and surface of constant curvature},
     journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a},
     pages = {150--164},
     publisher = {mathdoc},
     volume = {20},
     number = {1},
     year = {2023},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/SEMR_2023_20_1_a18/}
}