Phan, A., and N. Le. “Investigation of Stability of Colorant Powders Extracting from Japanese Purple Sweet Potato (Ipomoea Batatas (L.) Poir)”. Science and Technology Development Journal, Vol. 20, no. K7, Nov. 2018, pp. 28-34, doi:https://doi.org/10.32508/stdj.v20iK7.1208.