@article{MAN_1987__279_3_164311,
     author = {S\"onke Hansen},
     title = {The {Leading} {Singularity} of {Scattering} {Kernel} for a {Transparent} {Obstacle.}},
     journal = {Mathematische Annalen},
     pages = {125--140},
     publisher = {mathdoc},
     volume = {279},
     number = {3},
     year = {1987},
     zbl = {0609.35071},
     url = {http://geodesic.mathdoc.fr/item/MAN_1987__279_3_164311/}
}