KRISDIANTORO, S. E.; PRIHATNANI, E. Student’s thinking to identify concave plane based on Gregorc model. Beta: Jurnal Tadris Matematika, [S. l.], v. 12, n. 2, p. 109–121, 2019. DOI: 10.20414/betajtm.v12i2.338. Disponível em: https://mail.jurnalbeta.ac.id/index.php/betaJTM/article/view/338. Acesso em: 17 apr. 2026.