Ramadhani, Fitriana Dewi, Mustika Wati, Misbah Misbah, and Ketang Wiyono. 2021. “The Validity of Electronic Learning Materials Optical Instruments Based on Authentic Learning to Train Students’ Problem Solving Skills”. Kasuari: Physics Education Journal (KPEJ) 4 (2):78-89. https://doi.org/10.37891/kpej.v4i2.212.