-

-

http://www.thaigoodview.com/library/contest2551/tech04/22/standard/p01.html

http://www.lks.ac.th/anchalee/tec51.htm

-

-

-

-

-

http://www.gotoknow.org/posts/314100

http://dc338.4shared.com/doc/a4t84gCH/preview.html