Murugan K,Finney Daniel Shadrach,Anitha R, Jai Shankar B. “Facial Emotion Recognition Using Swarm Optimization Technique”. International Journal of Advanced Science and Technology, Vol. 29, no. 7s, Apr. 2020, pp. 1473 -80, http://sersc.org/journals/index.php/IJAST/article/view/10802.