Utilazation of different rate of urea fertilizer on lettuce, ការប្រើប្រាស់កំរិតជីអ៊ុយរ៉េខុសៗគ្នា លើដំណាំសាលាដ RA, YANITH. AGR RA 2011 B049 Or.1 Phnom Penh RUA 2011 2011 Text X, 42p. https://drive.google.com/file/d/1aLWFj6IX4Fv2zpEmlWMv6o-_yira3bFZ/view?usp=sharing