1 files changed, 2 insertions, 0 deletions

diff --git a/README.md b/README.md
index 154d9c9..4e82989 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,8 @@ Computer Systems: A Programmer's Perspective
 
 aka CMU 15213
 
+Explaination here: https://ov4.org/categories/csapp/ 
+
 I'm not going to publish Arch, Performance and Buffer lab cuz it's not in 15213 syllabus
 
 try my new project [Cache Simulator](https://github.com/ov-4/CacheSimulator) (upgraded version, support multiple levels of cache)