IRWANTO, J. .; KURNIATI, D. .; YUDIANTO, E. .; SANTOSO, K. A. . Assessing university student’s Van Hiele level of abstract thinking in-two variable linear equations using IRT: Implication for Economic Education. International Journal of Innovative Research and Scientific Studies, [S. l.], v. 8, n. 9, p. 113–126, 2025. DOI: 10.53894/ijirss.v8i9.10633. Disponível em: https://ijirss.com/index.php/ijirss/article/view/10633. Acesso em: 5 dec. 2025.