L. Firdaus, I. N. . Dewi, S. N. . Primawati, H. Hulyadi, S. Sabrun, and I. Azmi, “A Systematic Review of Threshold Concepts in Higher Education: Characteristics, Learning Barriers, and Pedagogical Interventions”, Inter. J. Essent. Comp. Edu, vol. 4, no. 2, pp. 117–124, Dec. 2025, doi: 10.36312/qerb8q19.