@article{DAN_1973_210_5_a5,
     author = {A. A. Kaplan},
     title = {Characteristic properties of penalty functions},
     journal = {Doklady Akademii Nauk},
     pages = {1018--1021},
     publisher = {mathdoc},
     volume = {210},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_210_5_a5/}
}