@article{SM_1989_62_2_a13,
     author = {Yu. V. Egorov and V. A. Kondrat'ev},
     title = {On an estimate of the number of points of the negative spectrum of the {Schr\"odinger} operator},
     journal = {Sbornik. Mathematics},
     pages = {551--566},
     publisher = {mathdoc},
     volume = {62},
     number = {2},
     year = {1989},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1989_62_2_a13/}
}