Charal Thong-Ngam. 1996. Changing roles of upland rice in diversified production systems in hilltribe village of Chiang Rai province. Graduate School, Chiang Mai University;
Charal Thong-Ngam. (1996) Changing roles of upland rice in diversified production systems in hilltribe village of Chiang Rai province . Chiang Mai University/Chiang Mai.
Charal Thong-Ngam. Changing roles of upland rice in diversified production systems in hilltribe village of Chiang Rai province. . Chiang Mai:Chiang Mai University, 1996.
Charal Thong-Ngam. (1996) Changing roles of upland rice in diversified production systems in hilltribe village of Chiang Rai province . Chiang Mai University/Chiang Mai.