Widyastuti, Z., and S. Widhiati. “Ceramide Is More Effective Than Shea Butter in Maintaining Skin Acidity”. Berkala Ilmu Kesehatan Kulit Dan Kelamin, vol. 34, no. 1, Mar. 2022, pp. 5-9, doi:10.20473/bikk.V34.1.2022.5-9.