@article{TMF_1977_31_2_a6,
     author = {M. V. Nikolaev and V. S. Ol'khovskii},
     title = {Analytic structure of the $S$ matrix for some classes of potentials},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {214--219},
     publisher = {mathdoc},
     volume = {31},
     number = {2},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1977_31_2_a6/}
}