diff --git a/docs/必学工具/tools.md b/docs/必学工具/tools.md
index 5e0ad40e..19c84f56 100644
--- a/docs/必学工具/tools.md
+++ b/docs/必学工具/tools.md
@@ -4,7 +4,7 @@
 
 - [Sci-Hub](https://sci-hub.se/): Elbakyan 女神向你挥手，旨在打破知识壁垒的革命性网站。
 - [Library Genesis](http://libgen.is/): 电子书下载网站。
-- [Z-library](https://z-lib.is/): 电子书下载网站（在 [Tor](https://www.torproject.org/) 下运行较佳，[链接](http://loginzlib2vrak5zzpcocc3ouizykn6k5qecgj2tzlnab5wcbqhembyd.onion/)）。
+- [Z-library](https://zlibrary-global.se/): 电子书下载网站（在 [Tor](https://www.torproject.org/) 下运行较佳，[链接](http://loginzlib2vrak5zzpcocc3ouizykn6k5qecgj2tzlnab5wcbqhembyd.onion/)）。
 - [Z-ePub](https://z-epub.com/): ePub 电子书下载网站。
 - [PDF Drive](https://www.pdfdrive.com/): PDF 电子书搜索引擎。
 - [MagazineLib](https://magazinelib.com/): PDF 电子杂志下载网站。
diff --git a/docs/深度学习/CS231.en.md b/docs/深度学习/CS231.en.md
new file mode 100644
index 00000000..c1d12bb4
--- /dev/null
+++ b/docs/深度学习/CS231.en.md
@@ -0,0 +1,18 @@
+# CS231n: CNN for Visual Recognition
+
+## Course Introduction
+
+- Affiliated Universities：Stanford
+- Prerequisites: Foundations of Machine Learning
+- Programming Languages：Python
+- Course Difficulty：🌟🌟🌟🌟
+- Estimated hours: 80 hours
+
+Stanford's CV introductory class, led by the giant of the computer field, Fei-Fei Li (the research team of the epoch-making famous dataset ImageNet in CV field), but its content is relatively basic and friendly, if you have taken CS230, you can directly start the Project as practice.
+
+## Course Resources
+
+- Course Website：<http://cs231n.stanford.edu/>
+- Course Video：<https://www.bilibili.com/video/BV1nJ411z7fe>
+- Course Materials: None
+- Coursework：<http://cs231n.stanford.edu/schedule.html>，3 Programming Assignments