@article{DAN_1977_234_4_a8,
     author = {G. D. Stepanov},
     title = {Criteria for sign regularity of the {Green's} function of a two-point boundary value problem},
     journal = {Doklady Akademii Nauk},
     pages = {765--767},
     publisher = {mathdoc},
     volume = {234},
     number = {4},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_234_4_a8/}
}