diff --git a/docs/数学基础/information.en.md b/docs/数学基础/information.en.md
index 92c74fbf..808215a5 100644
--- a/docs/数学基础/information.en.md
+++ b/docs/数学基础/information.en.md
@@ -8,7 +8,7 @@
 - Difficulty: 🌟🌟🌟
 - Class Hour: 100 hours
 
-This is MIT's introductory information theory course for freshmen, Professor Penfield has written a special textbook for this course as course notes, which is in-depth and interesting.
+This is MIT's introductory information theory course for freshmen, Professor Penfield has written a special [textbook](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-050j-information-and-entropy-spring-2008/syllabus/MIT6_050JS08_textbook.pdf) for this course as course notes, which is in-depth and interesting.
 
 ## Course Resources