@incollection{JEDP_1990____A6_0, author = {Ikawa, Mitsuru}, title = {On poles of scattering matrices for several convex bodies}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {6}, pages = {1--9}, publisher = {Ecole polytechnique}, year = {1990}, mrnumber = {91j:35212}, language = {en}, url = {http://www.numdam.org/item/JEDP_1990____A6_0/} }