SYAWAHID, M. Kemampuan Berfikir Formal Mahasiswa. Beta: Jurnal Tadris Matematika, [S. l.], v. 8, n. 2, p. 125–141, 2015. Disponível em: https://jurnalbeta.ac.id/index.php/betaJTM/article/view/30. Acesso em: 26 aug. 2026.