@article{RM_2004_59_3_a3,
     author = {Yu. V. Pokornyi and V. L. Pryadiev},
     title = {Some problems of the qualitative {Sturm--Liouville} theory on a~spatial network},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {515--552},
     publisher = {mathdoc},
     volume = {59},
     number = {3},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2004_59_3_a3/}
}