• http://thanapongkiatsujja.blogspot.com/2012/07/3.html• http://kroosuveera.blogspot.com/2011/09/blog-post_13.html• http://www.gotoknow.org/posts/314100• http://littleploybuta.blogspot.com/2012/08/3.html• http://ajpanisara.wordpress.com/ch3/