Gittins, Katie Max Planck Institute for Mathematics, Max Planck Society;
https://doi.org/10.4171/PM/2027 (Verlagsversion)
Gittins-Helffer_Courant-sharp Robin eigenvalues for the square and other planar domains_2019.pdf (Verlagsversion), 358KB
Gittins, K., & Helffer, B. (2019). Courant-sharp Robin eigenvalues for the square and other planar domains. Portugaliae Mathematica, 76(1), 57-100. doi:10.4171/PM/2027.