\Bibitem{Gad92} \by R.~R.~Gadyl'shin \paper Ramification of a multiple eigenvalue of the Dirichlet problem for the Laplacian under singular perturbation of the boundary condition \jour Mat. Zametki \yr 1992 \vol 52 \issue 4 \pages 42--55 \mathnet{http://mi.mathnet.ru/mzm4754} \mathscinet{http://mathscinet.ams.org/mathscinet-getitem?mr=1203951} \zmath{https://zbmath.org/?q=an:0816.35093} \transl \jour Math. Notes \yr 1992 \vol 52 \issue 4 \pages 1020--1029 \crossref{https://doi.org/10.1007/BF01210435} \isi{https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=Publons&SrcAuth=Publons_CEL&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=A1992LF91500024}