@article{DAN_1966_169_2_a9,
     author = {M. V. Fedoryuk},
     title = {Asymptotic behavior of eigenvalues and eigenfunctions of one-dimensional singular differential operators},
     journal = {Doklady Akademii Nauk},
     pages = {288--291},
     publisher = {mathdoc},
     volume = {169},
     number = {2},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_169_2_a9/}
}