diff --git a/README.md b/README.md
index 7ad2ec1..a90e10b 100644
--- a/README.md
+++ b/README.md
@@ -63,7 +63,7 @@ description: 在自己的领域里持续探索，衣带渐宽终不悔，为伊
 | **TED(**[**u**](https://www.youtube.com/c/TED/featured)**, )**                                                                  | **TEDx Talks(**[**u**](https://www.youtube.com/user/TEDxTalks/featured)**, )**                                                                                                                                                                                                         | **RealLifeLore(**[**u**](https://www.youtube.com/c/RealLifeLore/playlists)**, )**                                | **Improvement Pill(**[**u**](https://www.youtube.com/c/ImprovementPillChannel/playlists)**, )**                                |
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 | [**edx**](https://www.edx.org)                                                                                                  | [**freecourseweb**](https://freecourseweb.com)                                                                                                                                                                                                                                         | **Harvard University(**[**u**](https://www.youtube.com/c/harvard/playlists)**, )**                               | **GeoScience & GeoEnergy Webinars(**[**u**](https://www.youtube.com/channel/UCoIW2njFBhPNDlNFdF8Z9uA/videos)**, )**            |
-| [pdfdrive](https://www.pdfdrive.com/)                                                                                           | <p><strong>udacity</strong> <a href="https://cn.udacity.com"><strong>s</strong></a> <a href="https://www.youtube.com/c/Udacity/playlists"><strong>u</strong></a> <a href="https://www.youtube.com/channel/UCL9-bfld991n7mK2NAzuupA/videos"><strong>u</strong></a></p><p>Nanodegree</p> | [**z-lib**](https://z-lib.org) [v](https://www.youtube.com/watch?v=Ze1C1kyETi8) [s](https://z-lib.id/) Z-Library | [**Library Genesis / libgen**](https://libgen.is)**(**[**bak**](https://libgen.rs)**)**                                        |
+| [pdfdrive](https://www.pdfdrive.com/)                                                                                           | <p><strong>udacity</strong> <a href="https://cn.udacity.com"><strong>s</strong></a> <a href="https://www.youtube.com/c/Udacity/playlists"><strong>u</strong></a> <a href="https://www.youtube.com/channel/UCL9-bfld991n7mK2NAzuupA/videos"><strong>u</strong></a></p><p>Nanodegree</p> | [**z-lib**](https://z-lib.cc) [v](https://www.youtube.com/watch?v=Ze1C1kyETi8) [s](https://z-lib.org/) Z-Library | [**Library Genesis / libgen**](https://libgen.is)**(**[**bak**](https://libgen.rs)**)**                                        |
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 | [**ebook**](http://clg5.info/search?word=ebook-pdf)                                                                             | [**小白盘**](https://www.xiaobaipan.com)                                                                                                                                                                                                                                                  | [**多读**](http://www.duodu.cc)                                                                                    | [**微米电子书分享**](https://www.dzsfx.com)                                                                                           |
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