RewriteEngine on
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?wolf-store\.de(/.*)?$ [NC]
RewriteCond %{HTTP_REFERER} !^http://(www\.)?wolf-store\.com(/.*)?$ [NC]
RewriteRule \.(gif|jpg|GIF|JPG)$ http://www.wolf-store.de/nolink.gif [R,L]