@article{DAN_1973_210_4_a2,
     author = {V. V. Gudkov and A. Ya. Lepin},
     title = {On necessary and sufficient conditions for the solvability of certain boundary-value problems for a second-order ordinary differential equation},
     journal = {Doklady Akademii Nauk},
     pages = {760--762},
     publisher = {mathdoc},
     volume = {210},
     number = {4},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_210_4_a2/}
}