[الريم الجفول]

http://www.schoolarabia.net/fezia/le...oga/page-1.htm



http://www.phys4arab.net/vb/showthread.php?t=28768


http://www.alwgf.com/index.php?wgf=r...&lesson_id=271


http://www.schoolarabia.net/alm3rd_a...5/physics3.htm