1. http://www.theguardian.com/science/alexs-adventures-innumberland/2015/aug/10/attack-on-the-pentagon-results-in-discoveryof-new-mathematical-tile
2. https://en.wikipedia.org/wiki/Pentagonal_tiling
3. https://en.wikipedia.org/wiki/Tessellation
4. Mann C. , McLoud-Mann J. & Von Derau D. , Convex pentagons that admit -block transitive tilings, posted on ArXiv in October 2015: http://arxiv.org/abs/1510.01186