@article{IM2_1970_4_1_a11,
     author = {S. L. Blyumin and B. D. Kotlyar},
     title = {Hilbert{\textendash}Schmidt operators and the absolute convergence of fourier series},
     journal = {Izvestiya. Mathematics},
     pages = {215--223},
     year = {1970},
     volume = {4},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1970_4_1_a11/}
}