diff --git a/rl4co/models/zoo/am/model.py b/rl4co/models/zoo/am/model.py
index 685e7206..10b1dfb9 100644
--- a/rl4co/models/zoo/am/model.py
+++ b/rl4co/models/zoo/am/model.py
@@ -7,7 +7,7 @@
 
 
 class AttentionModel(REINFORCE):
-    """Attention Model based on REINFORCE.
+    """Attention Model based on REINFORCE: https://arxiv.org/abs/1803.08475.
 
     Args:
         env: Environment to use for the algorithm