JIA, Ligang. Online Course Learning Resource Recommendation Based on Difficulty Matching. International Journal of Emerging Technologies in Learning (iJET), [S. l.], v. 17, n. 22, p. pp. 156–169, 2022. DOI: 10.3991/ijet.v17i22.35123. Disponível em: https://online-journals.org/index.php/i-jet/article/view/35123. Acesso em: 29 mar. 2024.