@Article{ MazZuc15, author = { Mazzoleni, Dario and Zucco, Davide }, title = { Convex combinations of low eigenvalues, Fraenkel asymmetries and attainable sets }, journal = { ESAIM: COCV }, year = { 2017 }, doi = { 10.1051/cocv/2016017 }, pages = { }, URL = { http://cvgmt.sns.it/paper/2855/ }, note = { cvgmt preprint} }