@article{SM_1997_188_11_a4,
     author = {G. D. Stepanov},
     title = {Effective criteria for the~strong sign-regularity and the~oscillation property of {the~Green's} functions of two-point boundary-value problems},
     journal = {Sbornik. Mathematics},
     pages = {1687--1728},
     publisher = {mathdoc},
     volume = {188},
     number = {11},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1997_188_11_a4/}
}