Orapin Watanesk และ Lek Chankasem. (1998) Effect of Gibberellin (GA3) and Urea on Hybrid Rice Seed Production. <i>Thai Agricultural Research Journal</i>, <i>16</i>(3), 172-177.Orapin Watanesk และ Lek Chankasem. "Effect of Gibberellin (GA3) and Urea on Hybrid Rice Seed Production". Thai Agricultural Research Journal 16 (1998):172-177.Orapin Watanesk และ Lek Chankasem. Effect of Gibberellin (GA3) and Urea on Hybrid Rice Seed Production. Department of Agriculture:ม.ป.ท. 1998.