diff --git a/doc/geocoding_functions.md b/doc/geocoding_functions.md
index 228f056..46f6e4c 100644
--- a/doc/geocoding_functions.md
+++ b/doc/geocoding_functions.md
@@ -181,7 +181,7 @@ UPDATE {tablename} SET the_geom = cdb_geocode_namedplace_point({city_column}, {p
 
 The following functions provide a postal code geocoding service that can be used to obtain points or polygon results. The postal code polygon geocoder covers the United States, France, Australia and Canada; a request for a different country will return an empty response.
 
-**Note:** For the USA, US Census [Zip Code Tabulation Areas](https://www.census.gov/geo/reference/zctas.html) (ZCTA) are used to reference geocodes for USPS postal codes service areas.
+**Note:** For the USA, US Census [Zip Code Tabulation Areas](https://www.census.gov/geo/reference/zctas.html) (ZCTA) are used to reference geocodes for USPS postal codes service areas. See the [FAQs](http://docs.cartodb.com/faqs/datasets-and-data/#why-does-cartodb-use-census-bureau-zctas-and-not-usps-zip-codes-for-postal-codes) about datasets and data for details.
 
 ### cdb_geocode_postalcode_polygon(_postal_code text, country_name text_)