@article{IM2_1976_10_2_a9,
     author = {Kh. Kh. Murtazin},
     title = {On nonisolated singular points of the spectrum of elliptic operators},
     journal = {Izvestiya. Mathematics},
     pages = {393--411},
     year = {1976},
     volume = {10},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1976_10_2_a9/}
}