@article{10_1017_S0017089500003165,
     author = {Colton, David},
     title = {A reflection principle for solutions to the {Helmholtz} equation and an application to the inverse scattering problem{\textdagger}},
     journal = {Glasgow mathematical journal},
     pages = {125--130},
     year = {1977},
     volume = {18},
     number = {2},
     doi = {10.1017/S0017089500003165},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003165/}
}