1. A note on the generalized Dumbbell problem;Anné;Proc. Amer. Math. Soc.,1995
2. Scattering frequencies of resonators;Beale;Comm. Pure Appl. Math.,1973
3. A. Bendali, A. Tizaoui, S. Tordeux, J.P. Vila, Matching of asymptotic expansions for an eigenvalue problem with two cavities linked by a narrow hole, SAM Research Report, ETH Zürich, 2009, no. 17
4. Lower bounds on the interaction between cavities connected by a thin tube;Brown;Duke Math. J.,1994
5. Surface potentials and the method of matching asymptotic expansions in the Helmholtz resonator problem;Gadyl'shin;Algebra i Analiz,1992