Yanti, Iing Rika, et al. “PRELIMINARY RESEARCH PENGEMBANGAN MODUL BERBASIS PROBLEM BASED INSTRUCTION PADA MATA KULIAH FISIKA MATEMATIKA I DI STKIP PGRI SUMATERA BARAT”. PROSIDING SEMINAR NASIONAL FISIKA (E-JOURNAL), vol. 5, Oct. 2017, pp. SNF2016-RND, doi:10.21009/0305010205.