Pornpimol Chaiwanakupt และ Chantana Siripaibool; Nantakorn Boonkerd; Thianchai Arayangkoon. (1997) Improving Yield and Nitrogen Fixation on Soybean in Thailand. <i>Thai Agricultural Research Journal</i>, <i>15</i>(1), 4-23.Pornpimol Chaiwanakupt และ Chantana Siripaibool; Nantakorn Boonkerd; Thianchai Arayangkoon. "Improving Yield and Nitrogen Fixation on Soybean in Thailand". Thai Agricultural Research Journal 15 (1997):4-23.Pornpimol Chaiwanakupt และ Chantana Siripaibool; Nantakorn Boonkerd; Thianchai Arayangkoon. Improving Yield and Nitrogen Fixation on Soybean in Thailand. Department of Agriculture:ม.ป.ท. 1997.