Gan และ Yinbo. (1993) Nitrogen fertilizer management in vegetable soybeans. Chiang Mai University,:ม.ป.ท.Gan และ Yinbo. 1993. Nitrogen fertilizer management in vegetable soybeans. ม.ป.ท.:Chiang Mai University,;Gan และ Yinbo. Nitrogen fertilizer management in vegetable soybeans. ม.ป.ท.:Chiang Mai University, 1993. Print.