D. Fitriarni, E. . Eko Rifkowaty, M. Martanto, N. . Verawaty, and D. . Purwanto, “Phenol Levels And Antidiabetic Functional Drinks Combination Of Black Tea And Singkil (Premna serrafolia)”, JPPT, vol. 22, no. 3, pp. 267-278, Dec. 2022.