Simanjuntak, K. V., and B. A. R. Damanik. “THE EFFECT OF USING MOTHER TONGUE ON THE DEVELOPMENT OF COGNITIVE ABILITIES AND SECOND LANGUAGE IN EARLY CHILDHOOD”. Sindoro: Cendikia Pendidikan, vol. 8, no. 11, Dec. 2024, pp. 1-10, doi:10.9644/sindoro.v8i11.7547.