@article{DAN_1981_260_1_a6,
     author = {S. P. Novikov},
     title = {Multivalued functions and functionals. {An} analogue of the {Morse} theory},
     journal = {Doklady Akademii Nauk},
     pages = {31--35},
     publisher = {mathdoc},
     volume = {260},
     number = {1},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_260_1_a6/}
}