Unknown, “Comparison of Pithecanthropus, Neanderthal, and Cro-Magnon Man skulls,” AMNH Digital Special Collections, accessed…
Unknown, “Comparison of Pithecanthropus, Neanderthal, and Cro-Magnon Man skulls,” AMNH Digital Special Collections, accessed April 28, 2014, http://images.library.amnh.org/digital/items/show/5879