https://cel.archives-ouvertes.fr/cel-00392187 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Friday, June 5, 2009 - 4:30:46 PM Last modification on : Monday, June 8, 2009 - 10:07:31 AM Long-term archiving on: : Monday, October 15, 2012 - 11:56:10 AM