@article{DAN_1995_342_1_a9,
     author = {O. A. Godin},
     title = {An adiabatic invariant for acoustic modes in a nonhomogeneous},
     journal = {Doklady Akademii Nauk},
     pages = {36--39},
     publisher = {mathdoc},
     volume = {342},
     number = {1},
     year = {1995},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1995_342_1_a9/}
}