but you can check out The Leucther Report. This American gas chamber expert was the first person to do serious forensics at the death camps.
Leuchter built cyanide gas chambers for the USA penal system, and knew everything about Cyanide gas, how it worked, and what precautions had to be taken when using this deadly, heavy and highly flammable gas.
His evidence was used in a Canadian Court case and promptly suppressed.
His life and livelihood was destroyed.
As for the Ann Frank debate, some flags were raised when Ann makes mention of the Gas chambers in 1942. Yet she was isolated and locked away from the very outside world that didn't even know about the supposed gas chambers at that time.
Even if you don't want to believe any of this it makes an interesting study in propaganda.