Eakachai Prapalimrungsi และ Apichat Imyim. (2007) Removal of humic acids from synthetic wastewater by rice husk ash and modified rice husk ash. Chulalongkorn University:ม.ป.ท.Eakachai Prapalimrungsi และ Apichat Imyim. 2007. Removal of humic acids from synthetic wastewater by rice husk ash and modified rice husk ash. ม.ป.ท.:Chulalongkorn University;Eakachai Prapalimrungsi และ Apichat Imyim. Removal of humic acids from synthetic wastewater by rice husk ash and modified rice husk ash. ม.ป.ท.:Chulalongkorn University, 2007. Print.