@article{ISU_2007_7_2_a6,
     author = {Yu. V. Pokornyi and Zh. I. Bakhtina and A. S. Ishchenko},
     title = {On solvability of certain classes of irregular the second order variation problems},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {32--36},
     publisher = {mathdoc},
     volume = {7},
     number = {2},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ISU_2007_7_2_a6/}
}