https://cel.archives-ouvertes.fr/cel-00391890 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Friday, June 5, 2009 - 10:30:46 AM Last modification on : Monday, October 2, 2017 - 4:06:04 PM Long-term archiving on: : Friday, June 11, 2010 - 12:21:29 AM