Rahardja, Untung, Achmad Nizar Hidayanto, Panca Oktavia Hadi Putra, and Marviola Hardini. “Immutable Ubiquitous Digital Certificate Authentication Using Blockchain Protocol”. Journal of Applied Research and Technology 19, no. 4 (August 24, 2021): 308–321. Accessed May 2, 2024. https://jart.icat.unam.mx/index.php/jart/article/view/1046.