@Misc{ san08, author = { Santambrogio, Filippo }, title = { Absolute continuity and summability of transport densities: simpler proofs and new estimates }, journal = { Calc. Var. Par. Diff. Eq. }, year = { 2009 }, pages = { }, URL = { http://cvgmt.sns.it/paper/665/ }, note = { cvgmt preprint} }