http://www.jibbering.com/faq/notes/closures/
http://howtonode.org/why-use-closure
http://lostechies.com/derekgreer/2012/02/17/javascript-closures-explained/
http://robertnyman.com/2008/10/09/explaining-javascript-scope-and-closures/
http://www.webreference.com/programming/javascript/rg36/index.html
http://www.cn-cuckoo.com/2007/08/01/understand-javascript-closures-72.html
http://www.webreference.com/programming/javascript/rg36/index.html
http://www.cn-cuckoo.com/main/wp-content/uploads/2007/08/JavaScriptClosures.html
http://hi.baidu.com/setcookie/item/767c364a0d9671acdf2a9f0e
http://developer.51cto.com/art/201105/265514.htm
http://www.butlife.com/javascript-func-closure/
http://www.oschina.net/question/6981_25106
http://wenwen.soso.com/z/q172170576.htm
http://www.cnblogs.com/rubylouvre/archive/2009/07/24/1530074.html
http://www.ruanyifeng.com/blog/2009/08/learning_javascript_closures.html
http://www.cn-cuckoo.com/2007/08/01/understand-javascript-closures-72.html
http://www.cn-cuckoo.com/main/wp-content/uploads/2007/08/JavaScriptClosures.html#clEncap