Abd Rashid, Nur Amira, et al. “Evaluation of Butterfly Pea Flowers for Antioxidant Activity and Its Potential As Antioxidant Soap ”. Progress in Engineering Application and Technology, vol. 3, no. 1, June 2022, pp. 64-73, https://publisher.uthm.edu.my/periodicals/index.php/peat/article/view/6265.