diff --git a/love_letter/love_letter.py b/love_letter/love_letter.py
index 5364627..6967853 100644
--- a/love_letter/love_letter.py
+++ b/love_letter/love_letter.py
@@ -1,5 +1,7 @@
 #!/usr/bin/python3
 
+# https://www.hackerrank.com/challenges/the-love-letter-mystery
+
 import sys
 
 def char_distance(ca,cb):
diff --git a/service_lane/service_lane.py b/service_lane/service_lane.py
index 3e6dfb9..e99a01d 100644
--- a/service_lane/service_lane.py
+++ b/service_lane/service_lane.py
@@ -1,5 +1,7 @@
 #!/usr/bin/python3
 
+# https://www.hackerrank.com/challenges/service-lane
+
 import sys
 
 def nextints():
diff --git a/utopian_tree/utopian_tree.py b/utopian_tree/utopian_tree.py
index 28729fa..e9dbffb 100644
--- a/utopian_tree/utopian_tree.py
+++ b/utopian_tree/utopian_tree.py
@@ -1,5 +1,7 @@
 #!/usr/bin/python3
 
+# https://www.hackerrank.com/challenges/utopian-tree
+
 import sys
 
 def calcsize(cycles):