The renowned German reference work The Handbuch der Zoologie/Handbook of Zoology was founded in the 1920's by Professor Willi Kükenthal in Berlin and treated the complete animal kingdom from single cell organisms to mammals in eight thematic volumes: Volume I Protozoa, Porifera, Colenteratea, Mesozoa (1925); Volume II Worms (1933/34); Volume III Arthropoda ex. Insecta (1927/1932); Volume IV Arthopoda: Insecta; Volume V Solenogastres, Mollusca, Echinoderma (1925); Volume VI Pisces / Amphibia (1930); Volume VII Reptilia / Aves (1931); Volume VIII Mammalia. The Volumes Insecta (Eds. N.P. Kristensen, R.G. Beutel) and Mammalia (Eds. M.S. Fischer, H. Schliemann) continued publication into the present with the most recent contributions in English language.