diff --git a/docs/_sidebar.md b/docs/_sidebar.md
index 8676f41..2f08b47 100644
--- a/docs/_sidebar.md
+++ b/docs/_sidebar.md
@@ -4,4 +4,5 @@
 * [前言](./Preface.md)
 * [第一章：介绍](./ch1.md)
 * [第二章：复杂性的本质](./ch2.md)
-* [第三章：工作代码是不够的（战略与战术编程）](./ch3.md)
\ No newline at end of file
+* [第三章：工作代码是不够的（战略与战术编程）](./ch3.md)
+* [第四章：模块应该是深的](./ch3.md)
\ No newline at end of file