Abderrahmane Bendali, M'Barek Fares, Abdelkader Tizaoui and Sébastien Tordeux. (2012). Matched Asymptotic Expansions of the Eigenvalues of a 3-D Boundary-Value Problem Relative to Two Cavities Linked by a Hole of Small Size.
            <i>Communications in Computational Physics</i>. <i>11</i> (2).
            456-471.
         doi:10.4208/cicp.141209.280610s