Franz Halder
The book is based upon captured Nazi documents, the available diaries of propaganda minister Joseph Goebbels, of General Franz Halder, and of the Italian Foreign Minister Galeazzo Ciano, evidence and testimony from the Nuremberg trials, British Foreign Office reports, and the author's recollection of his six years in Germany (from 1934 to 1940) as a journalist, reporting on Nazi Germany for newspapers, the United Press International (UPI), and CBS Radio. The work was written and initially published in four parts, but a larger one-volume edition has become more common.