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[Discover] Wiki | CodeIgniter http://codeigniter.com/wiki/ReCAPTCHA/ (codeigniter captcha)
[Discover] tppCaptcha - ASCII PHP CAPTCHA - Professional Website Development and Consulting and PHP and MySQL ... http://www.thephppro.com/products/captcha/index.php?tppCaptchaUserData=42msd#demo (programming spam captcha security)
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[Discover] ESP-PIX http://gs264.sp.cs.cmu.edu/cgi-bin/post-query-pix-esp (programming spam captcha security)
[Discover] PHP Captcha Security http://www.white-hat-web-design.co.uk/articles/php-captcha.php (php captcha code programming)
[Discover] reCAPTCHA: Stop Spam, Read Books http://recaptcha.net/ (spam books captcha tools)
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[Discover] Drupal Captcha | Konigi http://konigi.com/interface/drupal-captcha (usability design captcha ideas)
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[Discover] tppCaptcha - ASCII PHP CAPTCHA http://www.thephppro.com/products/captcha/ (spam security programming php)
[Discover] Incorrect verification code WITHOUT anything entered | drupal.org http://drupal.org/node/135448 (captcha drupal)
[Discover] Inaccessibility of CAPTCHA http://www.w3.org/TR/turingtest/ (accessibility design spam antispam)
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