https://cel.archives-ouvertes.fr/cel-00391789 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Thursday, June 4, 2009 - 4:59:02 PM Last modification on : Friday, June 5, 2009 - 11:14:15 PM Long-term archiving on: : Friday, June 11, 2010 - 12:20:58 AM