Derma Watty Sihombing, Widianti Lestari, Nurindah Dwiyani, Rosna Yuherlina Siahaan, and Ronald Simanjuntak. “E-Portfolio Systems for Seafarer Competency Documentation: Blockchain-Enabled Digital Credentialing and Career Development Tracking”. IJISIT: International Journal of Computer Science and Information Technology 2, no. 2 (December 30, 2025): 119–132. Accessed March 28, 2026. https://www.ojs.literasisains.id/index.php/ijisit/article/view/51.