@Article{ cramal07a, author = { Crasta, Graziano and Malusa, Annalisa }, title = { On a system of partial differential equations of Monge-Kantorovich type. }, journal = { J. Differential Equations }, year = { 2007 }, volume = { 235 }, pages = { 484-509 }, URL = { http://cvgmt.sns.it/paper/138/ }, note = { cvgmt preprint} }