diff --git a/README.md b/README.md
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@@ -119,7 +119,7 @@ Check out my [repos](https://github.com/qazbnm456) 🐾 or say *hi* on my [Twitt
 ### Rails
 
 * [Rails 動態樣板路徑的風險](http://devco.re/blog/2015/07/24/the-vulnerability-of-dynamic-render-paths-in-rails/) - Written by [Shaolin](http://devco.re/blog/author/shaolin/).
-* [Rails Security](http://php.ph/wydrops/drops/Rails%20Security%20(%E4%B8%8A).pdf) - Written by [@qazbnm456](https://github.com/qazbnm456).
+* [Rails Security - First part](https://hackmd.io/s/SkuTVw5O-) - Written by [@qazbnm456](https://github.com/qazbnm456).
 
 <a name="introductions-angularjs"></a>
 ### AngularJS