Opastrakul, S. (2014). Effect of genotype, nitrogen fertilizer rate and time of drainage on yield, milling quality and economic returns of rice production / Somchit Opastrakul. Chiang Mai : Graduate School, Chiang Mai University, 1996.

Opastrakul, Somchit. Effect of Genotype, Nitrogen Fertilizer Rate and Time of Drainage On Yield, Milling Quality and Economic Returns of Rice Production / Somchit Opastrakul. Chiang Mai : Graduate School, Chiang Mai University, 1996, 2014.

Opastrakul, Somchit. Effect of Genotype, Nitrogen Fertilizer Rate and Time of Drainage On Yield, Milling Quality and Economic Returns of Rice Production / Somchit Opastrakul. Chiang Mai : Graduate School, Chiang Mai University, 1996, 2014.