Alifkhan, M. V. D., and S. A. . Laga. “Designing an E-Report System As a Digital Portfolio in Early Childhood Education in Surabaya Using the Waterfall Method”. Matrix : Jurnal Manajemen Teknologi Dan Informatika, vol. 14, no. 3, Dec. 2024, pp. 146-61, doi:10.31940/matrix.v14i3.146-161.