patents on the family. Recent research by Eckehart Schumacher-Gebler, IndraKupferschmid and Dan Reynolds has clarified many aspects of Akzidenz-Grotesk's
history of the geometric sans". FontShop. Retrieved 19 August 2015. Kupferschmid, Indra. "On Erbar and Early Geometric Sans Serifs". CJ Type. Retrieved 20