Prof Dr Rolf Denk, born in Düsseldorf in 1935, worked as a dermatologist in the Mainz University Hospital and afterwards in his own specialist practice in Rüsselsheim. In 1978 he and other collectors were among the founders of the European Union to Search for, Collect, and Preserve Primitive and Curious Money (EUCOPRIMO). In 1981 he took over the editing of the journal Der Primitivgeldsammler. After completing his medical career, he devoted himself more to the research of early indigenous means of payment. 110 own publications have appeared on this topic. In 2017 he published the monograph...