@article{SM_1973_20_2_a0,
     author = {K. I. Babenko},
     title = {On~summability and convergence of eigenfunction expansions of a~diffe\-rential operator},
     journal = {Sbornik. Mathematics},
     pages = {157--211},
     publisher = {mathdoc},
     volume = {20},
     number = {2},
     year = {1973},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1973_20_2_a0/}
}