@article{DAN_1973_212_1_a6,
     author = {S. A. Lomov},
     title = {Formalism of nonclassical perturbation theory},
     journal = {Doklady Akademii Nauk},
     pages = {33--36},
     publisher = {mathdoc},
     volume = {212},
     number = {1},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_212_1_a6/}
}