@article{SM_2020_211_11_a1,
     author = {D. V. Valovik},
     title = {On the integral characteristic function of the {Sturm-Liouville} problem},
     journal = {Sbornik. Mathematics},
     pages = {1539--1550},
     publisher = {mathdoc},
     volume = {211},
     number = {11},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2020_211_11_a1/}
}