diff --git a/system_design/README.md b/system_design/README.md
index 25c67a55..e961dcca 100644
--- a/system_design/README.md
+++ b/system_design/README.md
@@ -2,4 +2,7 @@
 
 ## Meterials
 - Books
-	- https://github.com/yennanliu/knowledge_base_repo/tree/master/book/system_design
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+	- https://github.com/yennanliu/knowledge_base_repo/tree/master/book/system_design
+- Others
+	- Sys Degisn By Example : https://third-bit.com/sdxpy/build/	
+		- code: https://github.com/yennanliu/sdxpy
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