กฤษฎารักษ์ฐ. and หงส์วริทธิ์ธรณ. (2012) “The Effects of Partial Occlusion in Image-based CAPTCHAs on Pass Rates”, JOURNAL OF INFORMATION SCIENCE AND TECHNOLOGY, 3(1), pp. 23-32. doi: 10.14456/jist.2012.4.