@article{TMF_1972_12_3_a7,
     author = {S. I. Manaenkov},
     title = {Perturbation theory for resonance and virtual states},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {397--406},
     publisher = {mathdoc},
     volume = {12},
     number = {3},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1972_12_3_a7/}
}