@article{DAN_1957_117_3_a4,
     author = {A. E. Martynyuk},
     title = {On a generalization of the variation method},
     journal = {Doklady Akademii Nauk},
     pages = {374--377},
     publisher = {mathdoc},
     volume = {117},
     number = {3},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_117_3_a4/}
}