Dienta, D.G.R.D. et al. 2026. Strengthening Logical Thinking in Children Aged 5-6 Years Through BUMIKA Geometry: A Classroom Action Research Study. Transformasi : Jurnal Penelitian dan Pengembangan Pendidikan Non Formal Informal. 12, 2 (Sep. 2026), 1010–1018. DOI:https://doi.org/10.33394/jtni.v12i2.19141.