Nukhba R, Wulandari IP, Ulum F, Parno P. Difficulty and Mastery of Physics Concepts for Middle School Students in Density Material. KPEJ [Internet]. 2024 Jun. 11 [cited 2026 Oct. 7];7(1):130-7. Available from: https://journalfkipunipa.org/index.php/kpej/article/view/522