Musyafirah, Syaila, and Usman Mulbar. “Needs Analysis and Design of Problem-Based Learning E-Book on Solid Geometry Material”. OMEGA: Jurnal Keilmuan Pendidikan Matematika 5, no. 2 (May 26, 2026): 257–266. Accessed June 5, 2026. https://www.ejurnal.univamedan.ac.id/index.php/jkpm/article/view/1276.