no. 4
Regularity of the Optimal Shape for the First Eigenvalue of the Laplacian With Volume and Inclusion Constraints
Annales de l'I.H.P. Analyse non linéaire, Tome 26 (2009) no. 4, pp. 1149-1163. 
@article{AIHPC_2009__26_4_1149_0,
     author = {Brian\c cOn, Tanguy and Lamboley, Jimmy},
     title = {Regularity of the Optimal Shape for the First Eigenvalue of the Laplacian With Volume and Inclusion Constraints},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {1149--1163},
     publisher = {Elsevier},
     volume = {26},
     number = {4},
     year = {2009},
     doi = {10.1016/j.anihpc.2008.07.003},
     zbl = {pre05590477},
     mrnumber = {2542718},
     language = {en},
     url = {www.numdam.org/item/AIHPC_2009__26_4_1149_0/}
}
BriançOn, Tanguy; Lamboley, Jimmy. Regularity of the Optimal Shape for the First Eigenvalue of the Laplacian With Volume and Inclusion Constraints. Annales de l'I.H.P. Analyse non linéaire, Tome 26 (2009) no. 4, pp. 1149-1163. doi : 10.1016/j.anihpc.2008.07.003. http://www.numdam.org/item/AIHPC_2009__26_4_1149_0/

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