@article{10_1090_S0894_0347_04_00452_7,
     author = {Burq, Nicolas and Zworski, Maciej},
     title = {Geometric control in the presence of a black box},
     journal = {Journal of the American Mathematical Society},
     pages = {443--471},
     publisher = {mathdoc},
     volume = {17},
     number = {2},
     year = {2004},
     doi = {10.1090/S0894-0347-04-00452-7},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-04-00452-7/}
}