http://blog.163.com/l1_jun/blog/static/14386388201441344612/

http://blog.chinaunix.net/uid-25073805-id-2984335.html

http://jingyan.baidu.com/article/948f59242fa71cd80ef5f910.html

http://www.gwa2011.com/bbs/forum.php?mod=viewthread&tid=76