Pseudonym the attempt was not entirely successful – and the two are still sometimes confused by booksellers. A pen name may be used specifically to hide the identity of the author, as in the case of exposé books about espionage or crime, or explicit erotic fiction. Some prolific authors adopt a pseudonym to disguise the extent of their published output, e.g. Stephen King writing as Richard Bachman. Co-authors may choose to publish under a collective pseudonym, e.g., P. J. Tracy and Perri O'Shaughnessy. Frederic Dannay and Manfred Lee used the name Ellery Queen as both a pen name for their collaborative
Pen name may use different pen names for each, sometimes with no attempt to conceal a true identity. Romance writer Nora Roberts writes erotic thrillers under the pen name J. D. Robb (such books are titled "Nora Roberts writing as J. D. Robb"); Scots writer Iain Banks wrote mainstream or literary fiction under his own name and published science fiction under Iain M. Banks; Samuel Langhorne Clemens used the aliases Mark Twain and Sieur Louis de Conte for different works. Similarly, an author who writes both fiction and non-fiction (such as the mathematician and fantasy writer Charles Dodgson, who wrote as Lewis