Rahardjo M, Karwur FF, Rondonuwu FS. Optical Properties and Relative Determination of Caffeine in Black Tea Liquor. J.Sains Dasar [Internet]. 2019 Oct. 15 [cited 2025 Jun. 2];8(2):45-9. Available from: https://journal.uny.ac.id/index.php/jsd/article/view/20781