From 2004 to 2007, under the title "Simply Droog", retrospectives took place in the Haus der Kunst in Munich, the Gemeentemuseum Den Haag, Museo Oscar Niemeyer in Curitiba (Brazil) and the Museum of Arts & Design in New York. On this occasion, a book was published about Droog, "Simply Droog: 10 + 1 years of creating innovation and discussion". This book was expanded and reissued in 2006 under the title "Simply Droog: 10 + 3 years of creating innovation and discussion."