@article{IVM_1973_6_a14,
     author = {L. D. \`Eskin},
     title = {The spectrum of singular differential operators},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {103--116},
     publisher = {mathdoc},
     number = {6},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1973_6_a14/}
}