|Other Retailer||Price Checked Time||Their Price in AUD||Our Price|
|Amazon UK||4 days ago||37.61||$25.19||You save $12.42|
|Amazon US||yesterday||32.65||$25.19||You save $7.46|
|Book Depository US||today||27.57||$25.19||You save $2.38|
Greg Ross edits the popular website Futility Closet, a collection of entertaining curiosities in history, literature, language, art, philosophy, and mathematics. Previously he spent 20 years editing science, engineering, and education publications for publishers such as IEEE, UNext.com, and American Scientist magazine. He lives in Raleigh, North Carolina.