1. Source for Figure 1: Image by “Fibonacci”, from a Wikipedia SVG file, created 16 March 2007, GNU Free Documentation License, Creative Commons Attribution ShareAlike 2.5, accessed on July 8 2014.]

2. Source for Figure 2: Posted to Flickr by Davee, taken on April 10, 2008, Creative Commons/Attribution 2.0 Generic License, accessed on June 2 2014.

3. Source for Figure 3: Copyright A. Kitaoka, September 2, 2003, from Akiyoshi’s illusion pages.

4. Source for Figure 4: Image by BenFrantzDale, from a Wikipedia SVG file, uploaded by “Fibonacci”, Creative Commons Attribution-ShareAlike 3.0 Unported license.