https://cel.archives-ouvertes.fr/cel-00372870 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Thursday, April 2, 2009 - 4:10:35 PM Last modification on : Friday, June 19, 2020 - 9:10:04 AM Long-term archiving on: : Thursday, June 10, 2010 - 6:05:40 PM