@article{DE_1974_10_1_a9,
     author = {S. K. Kumykova},
     title = {A certain problem with nonlocal boundary conditions on the characteristics for an equation of mixed type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {78--88},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1974_10_1_a9/}
}