L. Prieto, K. Sharma, Y. Wen, and P. Dillenbourg. Proceedings of the 11th International Conference on Computer-Supported Collaborative Learning (CSCL 2015), page 212-219. Gothenburg Sweden, (2015)
C. Jay, R. Stevens, M. Glencross, and A. Chalmers. Proceedings of W4A, International Cross-Disciplinary Workshop on Web Accessibility, page 113--120. Edinburgh, Scotland, ACM Press, (May 2006)