Prachya Watasit และ Sophon Roengsumran. (2008) Preparation of Silica adsorbent from rice husk ash. Chulalongkorn University:ม.ป.ท.Prachya Watasit และ Sophon Roengsumran. 2008. Preparation of Silica adsorbent from rice husk ash. ม.ป.ท.:Chulalongkorn University;Prachya Watasit และ Sophon Roengsumran. Preparation of Silica adsorbent from rice husk ash. ม.ป.ท.:Chulalongkorn University, 2008. Print.