@incollection{JEDP_1991____A13_0,
     author = {Beals, Michael and Strauss, Walter},
     title = {Time decay estimates for a perturbed wave equation},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {13},
     pages = {1--10},
     publisher = {Ecole polytechnique},
     year = {1991},
     mrnumber = {1132234},
     zbl = {0754.35078},
     language = {en},
     url = {http://archive.numdam.org/item/JEDP_1991____A13_0/}
}