@article{DAN_1977_235_5_a1,
     author = {V. F. Butuzov},
     title = {Angular boundary layer in singularly perturbed mixed problems for the second-order hyperbolic equations},
     journal = {Doklady Akademii Nauk},
     pages = {997--1000},
     publisher = {mathdoc},
     volume = {235},
     number = {5},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1977_235_5_a1/}
}