@Article{ bokbrizid09, author = { Bokanowski, Olivier and Briani, Ariela and Zidani, Hasnaa }, title = { Minumum time control problems for non autonomos differential equations. }, journal = { System and control letters }, year = { 2009 }, volume = { 58 }, pages = { 742-746 }, URL = { http://cvgmt.sns.it/paper/1299/ }, note = { cvgmt preprint} }