Tonra, W. S., D. Suryadi, E. C. Mulyaning, and Kusnandi. “Learning Obstacles and the Didactical Design for Teaching the Limit of Function in a Calculus Course”. Journal on Mathematics Education, vol. 16, no. 1, Feb. 2025, pp. 153-72, doi:10.22342/jme.v16i1.pp153-172.