@article{MZM_1970_7_6_a11,
     author = {D. R. Yafaev},
     title = {Negative spectrum of the {Schr\"odinger} operational equation},
     journal = {Matemati\v{c}eskie zametki},
     pages = {753--763},
     publisher = {mathdoc},
     volume = {7},
     number = {6},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1970_7_6_a11/}
}