diff --git a/tutorial-contents/405_DQN_Reinforcement_learning.py b/tutorial-contents/405_DQN_Reinforcement_learning.py
index 7b67892..b560d1b 100644
--- a/tutorial-contents/405_DQN_Reinforcement_learning.py
+++ b/tutorial-contents/405_DQN_Reinforcement_learning.py
@@ -1,6 +1,7 @@
 """
 View more, visit my tutorial page: https://morvanzhou.github.io/tutorials/
 My Youtube Channel: https://www.youtube.com/user/MorvanZhou
+More about Reinforcement learning: https://morvanzhou.github.io/tutorials/machine-learning/reinforcement-learning/
 
 Dependencies:
 torch: 0.1.11