Guillot, Agnès; Meyer, Jean-Arcady (2010) [Published in French in 2008]. How To Catch a Robot Rat: When Biology Inspires Innovation [La bionique: Quand la science imite la Nature]. Translated by Susan Emanuel. The MIT Press. էջ 212. ISBN978-0-262-01452-6. «Many insects and a few birds perceive polarized light. The Vikings used cordierite for this purpose, a stone that allowed them to reckon the position of the sun by observing the stone's changes in color.»
