historian Peter Hoffmann declared: Hoffman went on to write that though Irving had at one time played a useful role in the historical profession by making outrageous assertions that at least had the benefit of inspiring historians to undertake research to rebut him, the time for that had now passed, and that Irving was simply irrelevant to the study of the Third Reich. In a feuilleton published in the Frankfurter Allgemeine Zeitung on 18 October 1989 the German historian Rainer Zitelmann praised Irving for having "struck a nerve" with his provocative style and aggressive assertions. Zitelmann found much to be praised about Irving's claim that the lack of a written Führer order for the Holocaust suggests that Hitler was unaware of the Holocaust, and argued that if that was true, then historians should stop holding the Holocaust against Hitler. Zitelmann ended his article with the claim that "Irving must not be ignored. He has weaknesses [but he is] one of the best knowers of sources…[and has] contributed much to research". The British historian John Charmley commented that "Irving's sources, unlike the conclusions which he draws from them, are usually sound", and that Irving "has been unjustly ignored". 1990s In 1990, the American historian Peter Baldwin called Irving a historian who "has made a career of seeking to shift culpability for the worst atrocities from Hitler and to draw also the Allies into proximity with the outrages of the war". In 1992, Robert G. L. Waite called Irving's work "a calumny both on the victims of Hitler's terror and on historical scholarship". About Irving's claims of Hitler's ignorance of the Holocaust, Waite commented that "no one but Hitler had the authority to give the orders to murder more than six million people in the mist of war". In his book, A World at Arms (1994), the American historian Gerhard Weinberg described Irving as "notoriously unreliable", and criticised those historians who used Irving to support their arguments. The British historian John Keegan wrote in his book The Battle for History (1996): "Some controversies are entirely bogus, like David Irving's contention that Hitler's subordinates kept from him the facts of the Final Solution, the extermination of the Jews". In a 20 April 1996 review in The Daily Telegraph of Goebbels: Mastermind of the Third Reich, Keegan wrote that Irving "knows more than anyone alive about the German side of the Second World War",