@article{ZNSL_1975_51_a15,
     author = {D. R. Yafaev},
     title = {On the virtual state of {Schr\"odinger} equation},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {203--216},
     year = {1975},
     volume = {51},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1975_51_a15/}
}