Pxcaptcha Site

If you meant something else — like a paper on a specific topic (machine learning, cryptography, etc.) — just let me know the subject, and I’ll recommend a strong, accessible one.

If you're asking for a (e.g., in computer science, AI, security, or another field), here’s a well-cited example related to CAPTCHA / bot detection : “CAPTCHA: Using Hard AI Problems for Security” by von Ahn, Blum, Hopper, and Langford (Eurocrypt 2003) This is the foundational paper that introduced modern CAPTCHAs. You can find it via Google Scholar or sites like ACM/IEEE. pxcaptcha