@article{TMF_1977_31_3_a4,
     author = {Yu. M. Shirokov},
     title = {Perturbation theory with respect to {Planck's} constant},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {327--332},
     publisher = {mathdoc},
     volume = {31},
     number = {3},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1977_31_3_a4/}
}