@article{MZM_1991_50_4_a12,
     author = {L. A. Pastur and V. A. Tkachenko},
     title = {Geometry of the spectrum of the one-dimensional {Schr\"odinger} equation with a periodic complex-valued potential},
     journal = {Matemati\v{c}eskie zametki},
     pages = {88--95},
     publisher = {mathdoc},
     volume = {50},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_50_4_a12/}
}