Viyanti, Viyanti, Rizki Eka Shintya, Undang Rosidin, Agus Suyatna, and Noor Farawahidah. “Analysis of Project-Based Problem-Solving Skills of Optical Equipment Materials With Heller and Heller Steps”. Jurnal Pendidikan IPA Indonesia 14, no. 2 (June 30, 2025). Accessed December 5, 2025. https://journal.unnes.ac.id/journals/jpii/article/view/23810.