@article{DE_1975_11_10_a16,
     author = {A. G. Kuz'min},
     title = {Boundary value problems for equations of mixed type with characteristics that cross the line of degeneracy {twice.~I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1853--1861},
     publisher = {mathdoc},
     volume = {11},
     number = {10},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1975_11_10_a16/}
}