@article{MZM_1990_48_6_a18,
     author = {V. N. Kolokoltsov},
     title = {The {Maslov} index in infinite-dimensional symplectic geometry},
     journal = {Matemati\v{c}eskie zametki},
     pages = {142--145},
     publisher = {mathdoc},
     volume = {48},
     number = {6},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1990_48_6_a18/}
}