@incollection{JEDP_2001____A6_0,
     author = {Hitrik, Michael},
     title = {Expansions and eigenfrequencies for damped wave equations},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {6},
     pages = {1--10},
     publisher = {Universit\'e de Nantes},
     year = {2001},
     doi = {10.5802/jedp.590},
     mrnumber = {1843407},
     zbl = {01808682},
     language = {en},
     url = {http://www.numdam.org/articles/10.5802/jedp.590/}
}