I. Hidayat Shiddiq, M. Rasyid Ridho, Andi Nova, P. Lubis, Nurliani, and S. Nazwa, “The Relevance of Moral Development and Moral Education in Children (Kholbergh and Hamka Study)”, AL-MURABBI, vol. 13, no. 1, pp. 45-62, Aug. 2026.