@article{MZM_1979_25_4_a9,
     author = {M. Otelbaev},
     title = {A criterion for the resolvent of a {Sturm{\textendash}Liouville} operator to be kernel},
     journal = {Matemati\v{c}eskie zametki},
     pages = {569--572},
     year = {1979},
     volume = {25},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1979_25_4_a9/}
}