link

http://gpww.blog.163.com/blog/static/118268164200997103532110/

http://yishan.cc/blogs/gpww/archive/2009/10/08/2-1-catalan.aspx

http://bop1.wikispaces.com

http://tctop.wikispaces.com/

http://blog.sina.com.cn/s/blog_4a3096dd0100sbik.html

http://archive.cnblogs.com/a/2006575/

http://www.cnblogs.com/ACoder/

http://hi.csdn.net/morgan_xww