Jeffrey Tucker from the Brownstone Institute explains the censorship that he says happened (and still does) regarding the sale of books. In a fashion similar to the social media suppression of news articles and dissenting opinions, Tucker says online book sellers are either willingly supressing the marketing of books that dissent from narratives preferred by the government or are doing so under pressure from government officials.
For more information: https://brownstone.org/articles/book-burning-goes-digital/