@article{TM_1975_127_a8,
     author = {L. Stupyalis},
     title = {Initial-boundary value problems for equations of mixed type},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {115--145},
     year = {1975},
     volume = {127},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1975_127_a8/}
}