Papadimitriou, Sofia Theodor, and Maria Ioannis Niari. “Open Badges As Credentials in Open Education Systems: Case Studies from Greece and Europe”. Journal of Learning for Development 6, no. 1 (March 20, 2019). Accessed April 21, 2026. https://www.jl4d.org/index.php/ejl4d/article/view/311.