@article{FORUM_1991__3_2_186390,
     author = {P. Colli and Jos\'e-Francisco Rodriques},
     title = {Hyperbolic {Perturbation} {Problems} {Involving} {Time} {Derivatives} on the {Boundars.}},
     journal = {Forum mathematicum},
     pages = {205--218},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1991},
     zbl = {0738.35005},
     url = {http://geodesic.mathdoc.fr/item/FORUM_1991__3_2_186390/}
}