http://www.lesa.in.th/geo/rocks/rocks_index.htm
	http://www.lesa.in.th/geo/rocks/rocks.htm
	http://vdo.kku.ac.th/mediacenter/mediacenter-uploads/libs/html/1261/Rock_Mineral/Rock.htm
	http://www.thaiengineering.com/webboard/question.asp?QID=10541