@article{TSP_2007_26_26_a11,
     author = {Yu. V. Pokornyi and M. B. Zvereva and S. A. Shabrov},
     title = {Some questions of the qualitative theory of nonsmooth {Sturm-Liouville} problems},
     journal = {Trudy Seminara im. I.G. Petrovskogo},
     pages = {255--274},
     publisher = {mathdoc},
     volume = {26},
     number = {26},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TSP_2007_26_26_a11/}
}