Groom Lake/Area 51 Finally Declassified; Less Redacted CIA History Released Under FOIA.  National Security Archive Electronic Briefing Book No. 434 Posted – August 15, 2013 and edited by Jeffrey T. Richelson.
Central Intelligence Agency
Cropped version of <a rel="nofollow" class="external text" href="http://www2.gwu.edu/~nsarchiv/NSAEBB/NSAEBB434/images/Area-51-map.jpg">original</a> from National Security Archive at George Washington University (Electronic Briefing Book No. 434)