@article{DE_1972_8_1_a11,
     author = {A. M. Nakhushev},
     title = {On apriori estimates for the {Tricomi} and {Darboux} problems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {107--117},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_1_a11/}
}