diff --git a/Static-filter-syntax.md b/Static-filter-syntax.md
index 046ae30..d229225 100644
--- a/Static-filter-syntax.md
+++ b/Static-filter-syntax.md
@@ -190,7 +190,7 @@ All static extended filters can be declared to apply to a specific _entity_. For
 
     google.*###tads.c
 
-An _entity_ is defined as follow: a formal domain name with the Public Suffix part replaced by a wildcard.
+An _entity_ is defined as follow: a formal domain name with the [Public Suffix](https://publicsuffix.org) part replaced by a wildcard.
 
 Examples: `google.*`  will apply to all similar Google domain names: `google.com`, `google.com.br`, `google.ca`, `google.co.uk`, etc. Another example: `facebook.*` will apply to all similar Facebook domain names: `facebook.com`, `facebook.net`.