Amnat Suwanarit. 1989. Cumulative effects of urea and ammonium sulfate on the fourth-year corn grown on Pakchong soil. Bangkok:Kasetsart University;
Amnat Suwanarit. (1989) Cumulative effects of urea and ammonium sulfate on the fourth-year corn grown on Pakchong soil (รายงานผลงานวิจัย). Kasetsart University:Bangkok.
Amnat Suwanarit. Cumulative effects of urea and ammonium sulfate on the fourth-year corn grown on Pakchong soil. Bangkok:Kasetsart University, 1989.
Amnat Suwanarit. (1989) Cumulative effects of urea and ammonium sulfate on the fourth-year corn grown on Pakchong soil (รายงานผลงานวิจัย). Kasetsart University:Bangkok.