1. Anon., n.d. About Paul Ekman. [Online] Available at: https://www.paulekman.com/about/paul-ekman/.
2. Anon., n.d. Facial Action Coding System. [Online] Available at: https://lietome.fandom.com/wiki/Facial_Action_Coding_System.
3. Anon., n.d. Facial Action Coding System Affect Interpretation Dictionary (FACSAID). [Online] Available at: https://web.archive.org/web/20110809013135/http://face-and-emotion.com/dataface/facsaid/description.jsp.
4. Canedo, D., Trifan, A., & Neves, J. R., A (2018). Monitoring Students’ Attention in a Classroom Through Computer Vision. s.l (pp. 371–378). Springer International Publishing.
5. CHALASANI, R., n.d. Classrooms around the world. [Online] Available at: https://www.cbsnews.com/pictures/students-and-classrooms-around-the-world/17/.