@article{DAN_1977_232_6_a9,
     author = {V. I. Feigin},
     title = {Spectral asymptotic theory for boundary value problems, and the asymptotic behavior of the negative spectrum},
     journal = {Doklady Akademii Nauk},
     pages = {1269--1272},
     publisher = {mathdoc},
     volume = {232},
     number = {6},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_232_6_a9/}
}