5 links
Following Tracks
geocities.com
TRACCE Online Rock Art Bulletin paper on Namibian engravings and interpretation.
Rock art in Namibia
namibweb.com
General overview and information on location, meaning and protection of rock art.
Rock Art of Twyfelfontein
bradshawfoundation.com
A survey into the relationship between animal-engravings and cupules, by Maarten van Hoek