@article{MZM_2007_82_4_a11,
     author = {Yu. V. Pokornyi and M. B. Zvereva and A. S. Ishchenko and S. A. Shabrov},
     title = {An {Irregular} {Extension} of the {Oscillation} {Theory} of the {Sturm--Liouville} {Spectral} {Problem}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {578--582},
     publisher = {mathdoc},
     volume = {82},
     number = {4},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2007_82_4_a11/}
}