@article{EP_2009_27_a18,
     author = {Carlos Conca and Rajesh Mahadevan and Leon Sanz},
     title = {Shape derivative for a two-phase eigenvalue problem and optimal configurations in a ball},
     journal = {ESAIM. Proceedings},
     pages = {311--321},
     publisher = {mathdoc},
     volume = {27},
     year = {2009},
     doi = {10.1051/proc/2009034},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.1051/proc/2009034/}
}