Grisana Linwattana และ Virendra Pal Singh; Joveno S. Lales. (2002) The Extrapolation of Nitrogen Management Technology for Direct-Seeded Rice in Ubon Ratchathani Province Using Geographic Information System as a Tool. <i>Thai Agricultural Research Journal</i>, <i>20</i>(3), 237-249.Grisana Linwattana และ Virendra Pal Singh; Joveno S. Lales. "The Extrapolation of Nitrogen Management Technology for Direct-Seeded Rice in Ubon Ratchathani Province Using Geographic Information System as a Tool". Thai Agricultural Research Journal 20 (2002):237-249.Grisana Linwattana และ Virendra Pal Singh; Joveno S. Lales. The Extrapolation of Nitrogen Management Technology for Direct-Seeded Rice in Ubon Ratchathani Province Using Geographic Information System as a Tool. Department of Agriculture:ม.ป.ท. 2002.