F. I. Siregar, R. Nainggolan, N. Azizah, T. V. Sidauruk, and M. Kaban, “Effectiveness of Purple Cabbage Flower (Brassica oleracea var. capitata f. rubra) Extract as a Natural Indicator for Borax Identification in Food Products”, BIOCHEPHY:JSE, vol. 6, no. 1, pp. 105-112, Jun. 2026.