Balfour-Paul, Jenny.  Indigo: Egyptian Mummies to Blue Jeans.  Buffalo, NY: Firefly Books, 2012.

Ball, Philip.  Bright Earth, Art, and the Invention of Color.  London: Penguin Group, 2001.

Finlay, Victoria.  Color: A Natural History of the Palette.  New York, NY: Ballantine Books, 2002.

Gage, John.  Colour and Culture: Practice and Meaning from Antiquity to Abstraction.  London: Thames and Hudson Publishing, 1993.

McKinley, Catherine E.  Indigo: In Search of the Color That Seduced the World.  New York, NY: Bloomsbury USA, 2011.

Pastoureau, Michel.  Blue: The History of a Color.  Princeton, NJ: Princeton University Press, 2001.

Pleij, Herman.  Colors Demonic and Divine: Shades of Meaning in the Middle Ages and After.  Translated by Diane Webb.  New York, NY: Columbia University Press, 2004.