Nopharat Muangprasert และ Apichart Noeunplub; Sompong Pongput; Vichan Wittayasiri. (1997) Rainfed Paddy Soil Fertility Evaluation in Upper Northern Region for Effective Fertilizer Application. <i>Thai Agricultural Research Journal</i>, <i>15</i>(1), 55-65.Nopharat Muangprasert และ Apichart Noeunplub; Sompong Pongput; Vichan Wittayasiri. "Rainfed Paddy Soil Fertility Evaluation in Upper Northern Region for Effective Fertilizer Application". Thai Agricultural Research Journal 15 (1997):55-65.Nopharat Muangprasert และ Apichart Noeunplub; Sompong Pongput; Vichan Wittayasiri. Rainfed Paddy Soil Fertility Evaluation in Upper Northern Region for Effective Fertilizer Application. Department of Agriculture:ม.ป.ท. 1997.