Radovan, Marko, and Mojca Perdih. “Analysing Accessibility, Usability and Readability of Web-Based Learning Materials – Case Study of E-Learning Portals in Slovenia”. Journal of e-Learning and Knowledge Society 14, no. 1 (January 31, 2018). Accessed December 11, 2019. https://www.je-lks.org/ojs/index.php/Je-LKS_EN/article/view/1389.