@article{DE_1991_27_10_a15,
     author = {A. M. Minkin and L. A. Shuster},
     title = {Distribution of the spectrum and the convergence of spectral expansions for an operator of {Schr\"odinger} type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1778--1789},
     publisher = {mathdoc},
     volume = {27},
     number = {10},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_10_a15/}
}