https://cel.archives-ouvertes.fr/cel-01847567 Contributor : Bernard MultonConnect in order to contact the contributor Submitted on : Monday, July 23, 2018 - 4:22:06 PM Last modification on : Tuesday, February 4, 2020 - 1:24:47 AM Long-term archiving on: : Wednesday, October 24, 2018 - 3:57:57 PM