Readers can find information about books from the publisher, the author or possibly from a librarian. For some kinds of information, an individual may want to contact a biographer or literary agent of the author.
For information about specific books, the publisher of the book in question provides a trustworthy source. The publisher may also be able to initiate contact with the author of the book.
For information about books in general, librarians serve as a great resource, as they are specialists in research methods and information organization. Essays written by literary critics about a certain book or author offer additional insight.