@Article{ brabut, author = { Brancolini, Alessio and Buttazzo, Giuseppe }, title = { Optimal Networks For Mass Transportation Problems }, journal = { ESAIM Control Optim. Calc. Var. }, year = { 2005 }, doi = { 10.1051/cocv:2004032 }, volume = { 11 }, number = { 1 }, pages = { 88-101 }, URL = { http://cvgmt.sns.it/paper/70/ }, note = { cvgmt preprint} }