Vu, D. “Gemological Characteristics of Sapphire from Hong Liem, Ham Thuan Bac District, Binh Thuan Province, Viet Nam”. Science & Technology Development Journal: Natural Sciences, Vol. 4, no. 1, Apr. 2020, pp. 412-20, doi:https://doi.org/10.32508/stdjns.v4i1.594.