@inproceedings{bridges2008:417,
  author      = {McBurney, Susan},
  title       = {Mathematical Secrets of Seven},
  pages       = {417--420},
  booktitle   = {Bridges Leeuwarden: Mathematics, Music, Art, Architecture, Culture},
  year        = {2008},
  editor      = {Sarhangi, Reza and S\'{e}quin, Carlo H.},
  isbn        = {9780966520194},
  issn        = {1099-6702},
  publisher   = {Tarquin Publications},
  address     = {London},

  url         = {http://archive.bridgesmathart.org/2008/bridges2008-417.html}
}