Kumar, Vipin, and Atul Barve. “A Survey on Existing CAPTCHA Techniques and Proposed Gaming CAPTCHA for Better Security Analysis”. International Journal of Computer Sciences and Engineering 5, no. 1 (November 11, 2025): 101–106. Accessed February 2, 2026. https://ijcse.isroset.org/index.php/j/article/view/1341.