@Article{ Cri16, author = { Cristoferi, Riccardo }, title = { A second order local minimality criterion for the triple junction singularity of the Mumford-Shah functional }, journal = { ESAIM: COCV }, year = { 2018 }, volume = { 24 }, number = { 1 }, pages = { 401-435 }, URL = { http://cvgmt.sns.it/paper/2992/ }, note = { cvgmt preprint} }