@article{DAN_1974_219_1_a2,
     author = {R. M. Geidel'man and L. Z. Kruglyakov},
     title = {On planar surfaces},
     journal = {Doklady Akademii Nauk},
     pages = {19--22},
     publisher = {mathdoc},
     volume = {219},
     number = {1},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_219_1_a2/}
}