(in French) Ploster, Burkard, Eye Twisters: Ambigrams, Escher, and Illusions, web-based book available at http://www.maths.monash.edu.au/~bpolster/ambigram.html (date unknown) Ambigrams also feature prominently in Dan Brown's novel, Angels and Demons . Can you draw one for me? Unfortunately not at the moment, as I am busy with other projects. so am unable to design ambigrams