Abdjul, Tirtawaty, and Nova Ntobuo. 2018. “Developing Device of Learning Based on Virtual Laboratory through Phet Simulation for Physics Lesson With Sound Material”. International Journal of Sciences: Basic and Applied Research (IJSBAR) 39 (2): 105-15. https://www.gssrr.org/JournalOfBasicAndApplied/article/view/9002.