@article{DAN_1989_306_3_a5,
     author = {Yu. A. Mamedov},
     title = {Spectral problems for a system of ordinary differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {540--544},
     publisher = {mathdoc},
     volume = {306},
     number = {3},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_306_3_a5/}
}