@article{IVM_1990_3_a3,
     author = {I. S. Kats},
     title = {Thickness of the spectrum of a~singular string},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {23--30},
     publisher = {mathdoc},
     number = {3},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1990_3_a3/}
}