https://cel.archives-ouvertes.fr/cel-00374396 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Wednesday, April 8, 2009 - 3:17:20 PM Last modification on : Monday, October 5, 2020 - 2:32:02 PM Long-term archiving on: : Thursday, June 10, 2010 - 8:04:02 PM