E. Loviandari, B. H. C. Khosiyono, A. A. Masjid, A. F. Nisa, and T. Muti’ah, “Mathematics Learning with Concrete Manipulatives among Second-Grade Students at SDN Tridadi: A Perspective on the Concrete Operational Stage”, isej, vol. 7, no. 3, pp. 198-212, Sep. 2026.