@article{ZNSL_1981_109_a5,
     author = {V. N. Popov and M. M. Skriganov},
     title = {Remark on the spectrum structure of the two-dimensional {Schr\"odinger} operator with the periodic potential},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {131--133},
     publisher = {mathdoc},
     volume = {109},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1981_109_a5/}
}