https://cel.archives-ouvertes.fr/cel-00374409 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Wednesday, April 8, 2009 - 3:51:00 PM Last modification on : Wednesday, September 12, 2018 - 2:14:17 PM Long-term archiving on: : Thursday, June 10, 2010 - 8:04:20 PM