British library - http://blpc.bl.uk (2002-09-05)
Dict. de l'art moderne et contemporain / dir. de Gérard Durozoi, 1994
Karl Gerstern : first London exhibition, 1999
wikipedia.org, 2017-03-19
Information trouvée : Karl Gerstner (2 July 1930 – 1 January 2017) was a Swiss designer, typographer, author
and artist.