w3c subscribe

http://www.w3.org/html/ig/zh/

http://blog.csdn.net/spring21st/article/details/6126537

http://www.w3ctech.com/p/63

http://www.cnblogs.com/aNd1coder/archive/2011/03/10/1979376.html

http://foxling.org/js-ajax-dom/async-loading-js/