Motif: The Leuchter Report
The Leuchter Report, which is the report written by Fred Leuchter that apparently conclusively proves the Holocaust did not occur, appears over a hundred times in Denying History. In a sense, it is a dog whistle for neo-Nazis and deniers who need something to truly believe in their cause; it is, however, a deeply flawed report as Shermer points out.
Motif: The Gas Chambers
When the Holocaust is mentioned, naturally the gas chambers will be mentioned. And they are repeatedly mentioned in Denying History - first to give some history about the Holocaust, then when talking about the Leuchter Report, and finally in discussing how to prove the Holocaust really happened.
Symbol: The Swastika
Generally, whenever someone thinks about a Nazi, one of the first things that also pops into their heads is the Swastika, the symbol of the Nazi.
The Swastika is also symbolic of the death, destruction, and suffering brought on the world by Hitler and his insidious Nazi war machine.
Symbol: The Star of David
Another symbol of World War II and the Holocaust is the Star of David, which Jewish people were forced to wear to show that they were, in fact, Jews.
Ultimately, the Star of David is symbolic of the tremendous pain, destruction, and death the Jewish people had to endure during Hitler's reign of terror.
Allegory: Danse Macabre
Danse Macabre is an allegory of the Nazi death machine which resulted in the death of millions: that death was a universal no matter how well-off or connected the Jewish people were during World War II.