1. Authoring Tool Accessibility Guidelines, http://www.w3.org/WAI/intro/atag.php.
2. Firefox Web Accesibility Toolbar, https://www.mozilla.org/en US/firefox/new/?scene=2&utm_source=addons.mozilla.org&utm_medium=referral&utm_campaign=non-fx-button#download-fx.
3. HERA web accesibility tool, http://www.sidar.org/hera/.
4. Evaluating the accessibility of three open-source learning content management systems: a comparative study;Iglesias;Comput. Appl. Eng. Educ.,2014
5. An assessment of content quality in websites of basic and secondary Portuguese schools;Paula,2014