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 of the Roman Republic, and using it implied a positive intention. In pure mathematics, Nicolas Bourbaki is the pseudonym of a group of mostly French connected mathematicians attempting to expose the field in an axiomatic and self-contained, encyclopedic form. A pseudonym may be used to protect the writer for exposé books about espionage or crime. Former SAS soldier Steven Billy Mitchell used the pseudonym Andy McNab for his book about a failed SAS mission titled "Bravo Two Zero". The name Ibn Warraq ("son of a papermaker") has been used by dissident Muslim authors. Author Brian O'Nolan used the pen names