@article{IM2_1972_6_3_a8,
     author = {A. M. Sedletskii},
     title = {On biorthogonal expansions in exponential functions},
     journal = {Izvestiya. Mathematics },
     pages = {579--586},
     publisher = {mathdoc},
     volume = {6},
     number = {3},
     year = {1972},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1972_6_3_a8/}
}