Karmila, A., N. Arief, S. Friska, and L. Astuti. “A Development of E-Learning Chemistry Based on Project Based Learning on Buffer Solution Using Then Flipped Classroom Approach in Class XI SMA/MA”. INTERNATIONAL JOURNAL OF HIGH INFORMATION, COMPUTERIZATION, ENGINEERING AND APPLIED SCIENCE (JHICE), Vol. 2, no. 01, Jan. 2022, pp. 19-27, doi:10.24036/jhice/vol2-iss01/35.