@Misc{ PegSanXia17, author = { Pegon, Paul and Santambrogio, Filippo and Xia, Qinglan }, title = { A fractal shape optimization problem in branched transport }, journal = { J. Math. Pures Appl. }, year = { 2017 }, pages = { }, URL = { http://cvgmt.sns.it/paper/3562/ }, note = { cvgmt preprint} }