In his 2002 work "Black Sun", which was originally intended to trace the survival of occult Nazi themes in the postwar period, Goodrick-Clarke considered it necessary to readdress the topic. He devotes one chapter of the book to "the Nazi mysteries", as he terms the field of Nazi occultism there. Other reliable summaries of the development of the genre have been written by German historians. The German edition of "The Occult Roots of Nazism" includes an essay, "Nationalsozialismus und Okkultismus" ("National Socialism and Occultism"), which traces the origins of the speculation about Nazi occultism back to publications from the late 1930s, and which was subsequently translated by Goodrick-Clarke into English. The German historian Michael Rißmann has also included a longer "excursus" about "Nationalsozialismus und Okkultismus" in his acclaimed book on Adolf Hitler's religious beliefs.