According to 35:52 of this video
Most of the others - Barnes, Hoggan, App, Carto, Zündel, Irving, and Smith - have polemicized about the Holocaust, but not a single one of them has ever written even a single thoroughly researched and referenced article on the Holocaust, let alone a monograph.
David Irving has written well over 20 books on World War II, and caused quite an uproar with his 1977 book "Hitler's War" for his choice to not connect Hitler with the alleged holocaust.
As much as an uproar as he caused, to my understanding, "Hitler's War" is the Second World War from the point of view of Hitler, rather than a repudiation of the holocaust. But some people get angry when you depict Hitler as a human rather than the devil they would like you to believe that he is.
So it would be more accurate to define "Hitler's War" as a biography rather than one of the numerous books found on HolocaustHandbooks.