@Misc{ figrifvil11, author = { Figalli, Alessio and Rifford, Ludovic and Villani, Cédric }, title = { Tangent cut loci on surfaces }, journal = { Differential Geom. Appl. }, year = { 2011 }, pages = { }, URL = { http://cvgmt.sns.it/paper/1067/ }, note = { cvgmt preprint} }