Logo of the U.S. <b><a href="//commons.wikimedia.org/wiki/Category:National_Park_Service" title="Category:National Park Service">National Park Service</a></b>.
National Park Service
<a rel="nofollow" class="external free" href="http://www.nps.gov/hfc/services/identity/arrowheads.cfm">http://www.nps.gov/hfc/services/identity/arrowheads.cfm</a>, note <a rel="nofollow" class="external free" href="http://www.nps.gov/hfc/products/pubs/directive-93-07.cfm">http://www.nps.gov/hfc/products/pubs/directive-93-07.cfm</a>