https://cel.archives-ouvertes.fr/cel-00374738 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Thursday, April 9, 2009 - 3:38:52 PM Last modification on : Wednesday, July 18, 2018 - 8:11:27 PM Long-term archiving on: : Thursday, June 10, 2010 - 8:13:43 PM