جرب هذا اخي
http://www.google.dz/url?sa=t&rct=j&q=%D9%85%D8%B0%D9%83%D8%B1%D8%A9%2B%D8%AD%D8%A7%D9%84%D8%A9%20%D8%A7%D9%84%D8%AA%D9%88%D8%B8%D9%8A%D9%81%20%D9%81%D9%8A%20%D8%A7%D9%84%D9%88%D8%B8%D9%8A%D9%81%20%D8%A7%D9%84%D8%B9%D9%85%D9%88%D9%85%D9%8A&source=web&cd=8&ved=0CGsQFjAH&url=http%3A%2F%2Fbu.umbb.dz%2Fressources-electroniq%2Ftheses-n%2Fscience-economie-ar%2FTICHAT-Salwa.pdf&ei=WX8qUIudD4LG0QWT6IGYBQ&usg=AFQjCNFSY7jAV-ybFOGkGFwSuYPM6sXViw
وهذا
http://grh-management.blogspot.com/2011/01/blog-post_26.html
بالتوفيق