@article{MZM_1980_28_4_a6,
     author = {Kh. Kh. Murtazin and Ya. T. Sultanaev},
     title = {Formulas for the distribution of eigenvalues of nonsemibounded {Sturm--Liouville} operators},
     journal = {Matemati\v{c}eskie zametki},
     pages = {545--553},
     publisher = {mathdoc},
     volume = {28},
     number = {4},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1980_28_4_a6/}
}