@article{DE_1987_23_11_a23,
     author = {O. Ya. Savchenko},
     title = {On the eigenvalues of the {Sturm--Liouville} equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2006--2008},
     publisher = {mathdoc},
     volume = {23},
     number = {11},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_11_a23/}
}