http://hal.in2p3.fr/in2p3-00020546 Contributor : Suzanne RobertConnect in order to contact the contributor Submitted on : Wednesday, March 3, 1999 - 12:24:16 PM Last modification on : Wednesday, September 16, 2020 - 4:07:08 PM Long-term archiving on: : Monday, September 10, 2012 - 6:11:32 PM