Amel Ghazi, 15 Apr 2013 cet article svp http://link.springer.com/chapter/10.1007%2F978-94-011-3610-5_15#page-1
Amel Ghazi, 15 Apr 2013 et article svp http://link.springer.com/chapter/10.1007%2F978-94-011-3610-5_15#page-1