Kanokporn Bunnumma. 1989. The study on humic acid extraction from peat and its application to the paddy field. Faculty of Graduate Studies, Mahidol University;
Kanokporn Bunnumma. (1989) The study on humic acid extraction from peat and its application to the paddy field . Mahidol University/Bangkok.
Kanokporn Bunnumma. The study on humic acid extraction from peat and its application to the paddy field. . Bangkok:Mahidol University, 1989.
Kanokporn Bunnumma. (1989) The study on humic acid extraction from peat and its application to the paddy field . Mahidol University/Bangkok.