Wongchana, Boonchana, Montree Issarakraiasila, and Somsak Maneepong. 2011. “Nitrogen and Zinc on Growth and Nutrient Concentrations in Leaf of Pummelo Cv. Kao - Thongdee (Citrus Maxima (Burm.) Merr ”. Thai Agricultural Research Journal 29 (3):248-61. https://doi.org/10.14456/thaidoa-agres.2011.19.