https://cel.archives-ouvertes.fr/cel-00374620 Contributor : Cimpa CimpaConnect in order to contact the contributor Submitted on : Thursday, April 9, 2009 - 10:34:39 AM Last modification on : Tuesday, March 20, 2018 - 2:48:45 PM Long-term archiving on: : Friday, October 12, 2012 - 4:27:57 PM