Nguyên, Hoài-MinhNguyen, H. L.2016-01-132016-01-132016-01-13201510.1090/btran/7https://infoscience.epfl.ch/handle/20.500.14299/122212Cloaking using complementary media for the Helmholtz equation and a three spheres inequality for second order elliptic equationstext::journal::journal article::research article