Zulkardi, R. C. I. Prahmana, and R. I. I. Putri. “In Memory of Jan De Lange and Kees Hoogland: Honoring Their Legacy and Contributions to Mathematics Education in Indonesia”. Journal on Mathematics Education, vol. 16, no. 2, July 2025, pp. 753-62, doi:10.22342/jme.v16i2.pp753-762.