Soviet or Nazi nature". For a decade, Herde researched the months of August and September in the National Archives and Records Administration in Washington, where millions of pages of listening material are stored. This resulted in a study published in 2018 on the triangular relationship between the European Axis powers, Japan and the USSR during the Second World War. Half of the study consists of documentation. The sources it contains are telegrams sent between the Foreign Ministry in Tokyo and its diplomatic or consular missions abroad, intercepted and decoded by US agencies from 1942 onwards. Honours and memberships Herde has been awarded numerous scientific honors and memberships for his research. He is an elected member of many scientific societies, academies and commissions, including the Scientific Society at the Johann Wolfgang Goethe University Frankfurt am Main (since 2010 as honorary member), the "Gesellschaft für fränkische Geschichte", the , the Medieval Academy of America, the Royal Historical Society in London and the (since 1970). Celestine's birthplace, Sant'Angelo Limosano, has made him an honorary citizen for his work on this pope and saint. He accepted a guest professorship from 1966 to 1967 at the University of California, Berkeley. Among his academic students were Robert Helmholtz, Milo Kearney and John McCullough. Further visiting professorships led Herde to the University of Washington in 1971, to the Institute for Advanced Study in Princeton in 1971/72 and 1984, to the University of Chicago in 1973 and to Dumbarton Oaks in 1979. In 1998 he was honored on his 65th birthday with an extensive commemorative publication. On the occasion of his 70th birthday in 2003 Herde was honoured by a scientific colloquium in Lorsch an der Bergstraße and in 2008 by another colloquium. Herde declined calls to the University of California in Los Angeles as successor of Gerhart B. Ladner and to the Ludwig-Maximilians-University in Munich as successor of Peter Acht. Writings Monographs Beiträge zum päpstlichen Kanzlei- und Urkundenwesen im dreizehnten Jahrhundert (Münchener historische Studien, Abteilung Geschichtliche Hilfswissenschaft. Vol. 1). Lassleben, Kallmünz/Opf. 1961, 2nd edition 1967; plus Dissertation, Munich 1962. Audientia litterarum contradictarum. Untersuchungen über die päpstlichen Justizbriefe und die päpstliche Delegationsgerichtsbarkeit vom 13. bis zum Beginn des 16. Jahrhunderts (Bibliothek des Deutschen Historischen Instituts in Rom. Vols. 31 and 32). 2 volumes, Niemeyer, Tübingen 1970, , zugleich Habilitationsschrift, Munich 1965. Dante als Florentiner Politiker (Frankfurter historische Vorträge. Issue 3). Steiner, Wiesbaden 1976, . Karl I. von Anjou