กฤษฎารักษ์ ฐปกรณ์, and หงส์วริทธิ์ธร ณัฐธนนท์. 2012. “The Effects of Partial Occlusion in Image-Based CAPTCHAs on Pass Rates”. JOURNAL OF INFORMATION SCIENCE AND TECHNOLOGY 3 (1):23-32. https://doi.org/10.14456/jist.2012.4.