- David Krejčiřík, Vladimir Lotoreichik, Tuyen Vu, “Reverse Isoperimetric Inequality for the Lowest Robin Eigenvalue of a Triangle”, Appl Math Optim, 88, no. 2, 2023, 63

- Nicolas Popoff, Spectral Theory and Mathematical Physics, 2020, 229

- P. Acampora, A. Celentano, E. Cristoforoni, C. Nitsch, C. Trombetti, “A Spectral Isoperimetric Inequality on the n-Sphere for the Robin-Laplacian with Negative Boundary Parameter”, J Geom Anal, 35, no. 6, 2025, 183
