PGA.md

@@ -68,6 +68,7 @@ The PGA also aims to initiate discussions at the regional level through various
 
 ## Reference
 
+- https://www.nadir.org/nadir/initiativ/agp/free/pga/hallm.htm
 - https://pgaconference.poivron.org/general/en_hallmarks.html
 - http://www.sterneck.net/politik/pga-hallmarks/index.php
 - https://en.wikipedia.org/wiki/Peoples_Global_Action