Nhung, Dang, et al. “Method Optimization and Determination of the Contentsof Iron, Copper and Zinc Microelements in Raw Materials and Animal Feed Using the Atomic Absorption Spectrophotometry”. Vietnam Journal of Agricultural Sciences, vol. 21, no. 1, May 2024, pp. 53-64, http://testtapchi.vnua.edu.vn/index.php/vjasvn/article/view/1088.