Pichai Suvanprapaporn. (1991) Study and analysis of the salt efforesence production process in the Northeastern Thailand : a case study of Ban Muang district and Wanon Niwat district, Sakon Nakhon Province. Mahidol University,:ม.ป.ท.Pichai Suvanprapaporn. 1991. Study and analysis of the salt efforesence production process in the Northeastern Thailand : a case study of Ban Muang district and Wanon Niwat district, Sakon Nakhon Province. ม.ป.ท.:Mahidol University,;Pichai Suvanprapaporn. Study and analysis of the salt efforesence production process in the Northeastern Thailand : a case study of Ban Muang district and Wanon Niwat district, Sakon Nakhon Province. ม.ป.ท.:Mahidol University, 1991. Print.