@Article{ FraPal13, author = { Franzina, Giovanni and Palatucci, Giampiero }, title = { Fractional $p$-eigenvalues }, journal = { Riv. Mat. Univ. Parma }, year = { 2014 }, volume = { 5 }, number = { 2 }, pages = { 373-386 }, URL = { http://cvgmt.sns.it/paper/2168/ }, note = { cvgmt preprint} }