@article{TMF_1988_74_1_a7,
     author = {V. V. Dyakin and S. I. Petrukhnovskii},
     title = {On discreteness of~the~spectrum of~some operator sheaves associated with a~periodic {Schr\"odinger} equation},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {94--102},
     year = {1988},
     volume = {74},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1988_74_1_a7/}
}