What are examples of books being censored in Fahrenheit 451?

Throughout Ray Bradbury's masterpiece Fahrenheit 451, the idea of literature—and books in general—becoming illegal plays a pivotal role in the plot and underlying meaning of the novel. The novel tells of a dystopian society in which books are outlawed and criminalized. In this society, instead of putting out fires and saving lives, firemen start fires to burn books. When Guy Montag, the novel's protagonist, questions the fire chief, Captain Beatty, about the importance of burning and banning the books, Beatty replies, "We stand against the small tide of those who want to make everyone unhappy with conflicting theory and thought" (67). What Beatty means is that because literature is inherently intellectual, its existence is troubling. Literature discusses many important, yet arguable, aspects of life, including religion, politics, philosophy, existence, and life itself. The books have been banned to keep the citizens happy, dull, and uneducated. In other words, ignorance is bliss.
Towards the end of the novel, Montag meets other outcasts like himself who have abandoned their society in favor of a literature-based, intellectual life. Instead of hiding books, they memorize them and, in a way, become the books. Montag, for example, memorizes the Book of Revelation from the Christian Bible. This drives home one of the main ideas of Fahrenheit 451—that books cannot truly be banned or outlawed, for the ideas they contain are universal, intangible, and indestructible.