@article{JEDP_1985___1_A5_0,
     author = {Ikawa, Mitsuru},
     title = {On the poles of the scattering matrix for two convex obstacles},
     journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {5},
     pages = {1--14},
     publisher = {Ecole polytechnique},
     number = {1},
     year = {1985},
     zbl = {0587.35057},
     language = {en},
     url = {http://www.numdam.org/item/JEDP_1985___1_A5_0/}
}