Revisitar la història amb GIS, Gettysburg <a href="http://www.smithsonianmag.com/history-archaeology/Looking-at-the-Battle-of-Gettysburg-Through-Robert-E-Lees-Eyes-180014191.html?c=y&page=1">http://www.smithsonianmag.com/history-archaeology/Looking-at-the-Battle-of-Gettysburg-Through-Robert-E-Lees-Eyes-180014191.html?c=y&page=1</a><br>
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