I'm not going to link it because I don't want to spread it, but it's in Chapter 10, after the main character is fully adopted into the "organization." He's given a book to read only called "the book" that describes why he needs to be a white supremacist. With the context clues of a "great one" who was born in 1889, it's clear "the book" is Mein Kampf or some kind of collection of Nazi theory