The portrait collection comprises some 25,000 sheets.Initially, Series A of the catalogue consisted of 28 picture books. The nine text volumes provide biographical and bibliographical details on the portrayed persons, descriptions of the portraits as well as information on the artist and the respective technique. The supplement complements another 3,000 portraits, acquired after the beginning of this publication, and about 600 further portraits in other techniques and from various other sources. The work includes seven index volumes containing 15 single indexes.