S. W. Erdnase is a pseudonym used by the author of The Expert at the Card Table, a book detailing sleight of hand, cheating and legerdemain using playing cards. Still considered essential reading for any card magician, the book (usually known as just Erdnase, Expert, TEATCT, or sometimes the Bible) has been in publication since 1902. Erdnase's true identity is one of the enduring mysteries of the magic community. Source: Wikipedia (en)