Pichai Saranrom, “ Relative Efficiency of Prilled Urea, Urea Supergranules (USG), and Coated USG by Neem (Azadirachta indica) and Dicyandiamide on Transplanted Rice”, Agr. Nat. Resour., vol. 24, no. 2, pp. 176–186, Jun. 1990.