@article{04048278, title = {An inverse problem for Helmholtz's equation.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {10}, year = {1987}, pages = {825-827}, doi = {10.1155/S0161171287000929}, zbl = {0643.35110}, language = {en}, url = {http://dml.mathdoc.fr/item/04048278} }
Ramm, A.G. An inverse problem for Helmholtz's equation.. International Journal of Mathematics and Mathematical Sciences, Tome 10 (1987) pp. 825-827. doi : 10.1155/S0161171287000929. http://gdmltest.u-ga.fr/item/04048278/