Bakri, F., S. Sunaryo, V. F. Irawan, and D. Muliyati. “E-Learning Model for Problem Based Learning on Heat and Thermodynamic Topics in High School”. Jurnal Penelitian & Pengembangan Pendidikan Fisika, Vol. 4, no. 2, Dec. 2018, pp. 101 -2, doi:10.21009/1.04207.