@article{DE_1993_29_2_a11,
     author = {T. I. Kiguradze},
     title = {Periodic boundary value problems for linear hyperbolic equations. {I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {281--297},
     publisher = {mathdoc},
     volume = {29},
     number = {2},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1993_29_2_a11/}
}