Each volume contains an introduction in German and English, an explanation of the catalogue system, a German-English glossary, a bibliography, and indexes. All the entries are illustrated and include catalogue numbers, technical descriptions, measurements, references to related works, details of provenance and location, relevant literature, and a list of exhibitions and auctions in which works have appeared. Klee's own entries from the catalogue he maintained from 1911 onward are also included, and the most important works are illustrated in color.
In 1939, Klee was settled in Berne. His work from the period, especially the masks, alludes to the political situation in Europe and reflects Klee's consciousness of threat. Over 1000 illustrations, 100 in color.
