@article{TMF_1977_30_3_a8,
     author = {V. A. Knyr and Yu. F. Smirnov and K. V. Shitikova},
     title = {Group of canonical transformations and the method of $K$ harmonics},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {370--381},
     publisher = {mathdoc},
     volume = {30},
     number = {3},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1977_30_3_a8/}
}