%0 Journal Article %A Perthame, Benoı̂t %A Vega, Luis %T Energy concentration and Sommerfeld condition for Helmholtz and Liouville equations %J Comptes Rendus. Mathématique %D 2003 %P 587-592 %V 337 %N 9 %I Elsevier %U http://archive.numdam.org/articles/10.1016/j.crma.2003.09.006/ %R 10.1016/j.crma.2003.09.006 %G en %F CRMATH_2003__337_9_587_0