@article{01209879,
title = {On unique solvability of the periodic problem in the plane for linear hyperbolic equations.},
journal = {Memoirs on Differential Equations and Mathematical Physics},
volume = {12},
year = {1997},
pages = {129-131},
zbl = {0910.35072},
language = {en},
url = {http://dml.mathdoc.fr/item/01209879}
}
Kiguradze, T. On unique solvability of the periodic problem in the plane for linear hyperbolic equations.. Memoirs on Differential Equations and Mathematical Physics, Tome 12 (1997) pp. 129-131. http://gdmltest.u-ga.fr/item/01209879/