@article{GDZPPN002343754,
title = {Estimates of the Friedrichs -Lewy type for a hyperbolic equation with three characteristics},
journal = {Mathematica Scandinavica},
volume = {3},
year = {1955},
pages = {115-123},
zbl = {0064.34405},
url = {http://dml.mathdoc.fr/item/GDZPPN002343754}
}
THOMÉE, VIDAR. Estimates of the Friedrichs -Lewy type for a hyperbolic equation with three characteristics. Mathematica Scandinavica, Tome 3 (1955) pp. 115-123. http://gdmltest.u-ga.fr/item/GDZPPN002343754/