S. SUWANPAKDEE, S. DIREKBUSARAKOM, P. CHOTIPUNTU, and P. SONGSANGJINDA, “Urea as a Nitrogen Source in a Black Tiger Shrimp (Penaeus monodon) Closed Culture System”, Walailak J Sci & Tech, vol. 7, no. 2, pp. 135–140, Nov. 2011.