CHAROENPONG, Theekapun, and Patarida SANITTHAI. 2014. “A New Algorithm to Detect Occluded Face from a Head Viewpoint Using Hough Transform and Skin Ratio”. Walailak Journal of Science and Technology (WJST) 12 (1):35-49. https://wjst.wu.ac.th/index.php/wjst/article/view/1204.