@article{DAN_1988_299_1_a8,
     author = {L\^e H\^ong V\^an and A. T. Fomenko},
     title = {Lagrangian manifolds and the {Maslov} index in the theory of minimal},
     journal = {Doklady Akademii Nauk},
     pages = {42--45},
     publisher = {mathdoc},
     volume = {299},
     number = {1},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1988_299_1_a8/}
}