diff --git a/doc/manual_generated/parking-domains-ns.md b/doc/manual_generated/parking-domains-ns.md
index fc91c81..3c7fd78 100644
--- a/doc/manual_generated/parking-domains-ns.md
+++ b/doc/manual_generated/parking-domains-ns.md
@@ -1,5 +1,7 @@
 # Parking domain by name server
 
+Source: https://trends.builtwith.com/parked/traffic/Entire-Internet
+
 - parkingcrew.net
 - sedoparking.com
 - above.com