Henrot, A., and D. Zucco. “Optimizing the First Dirichlet Eigenvalue of the Laplacian With an Obstacle”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, vol. 19, no. 4, Dec. 2019, pp. 1535-59, doi:10.2422/2036-2145.201702_003.