@article{MZM_1991_50_6_a16,
     author = {K. Kh. Boimatov and Ya. T. Sultanaev},
     title = {Estimation of the negative spectrum of a lower semibounded self-adjoint operator},
     journal = {Matemati\v{c}eskie zametki},
     pages = {142--145},
     publisher = {mathdoc},
     volume = {50},
     number = {6},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_50_6_a16/}
}