@article{DAN_1975_221_1_a5,
     author = {I. Ya. Oleksiv},
     title = {On the area of a simple surface},
     journal = {Doklady Akademii Nauk},
     pages = {30--31},
     publisher = {mathdoc},
     volume = {221},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_221_1_a5/}
}