@article{SM_1972_18_4_a1,
     author = {V. A. Tkachenko},
     title = {On the expansion of an entire function of finite order in the eigenfunctions of a~differential operator},
     journal = {Sbornik. Mathematics},
     pages = {559--570},
     publisher = {mathdoc},
     volume = {18},
     number = {4},
     year = {1972},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1972_18_4_a1/}
}