Alifkhan MVD, Laga SA. Designing an e-report system as a digital portfolio in early childhood education in Surabaya using the waterfall method. MATRIX [Internet]. 2024 Dec. 9 [cited 2024 Dec. 22];14(3):146-61. Available from: https://ojs2.pnb.ac.id/index.php/MATRIX/article/view/2171