There aren't many stories that last through the millennia, but those that do tend to find themselves adapted and updated in numerous ways, few more so than the legend of King Arthur. Bibliophiles have been collecting books in the Arthurian vein for centuries, and they're a powerful source for writers of speculative fiction and non-speculative fiction. Perhaps the best known sources are Thomas Malory's Le Morte D'Arthur, Richard Blackmore's Prince Arthur and King Arthur, and the foundational works of Chretien de Troyes and Geoffrey of Monmouth. These have led to classic works such as T.H. White's The Sword in the Stone and The Once and Future King, Mark Twain's A Connecticut Yankee in King Arthur's Court, and Marion Zimmer Bradley's The Mists of Avalon. Collecting Arthurian books is a rewarding stream of collecting, with hundreds of books in print at a variety of price and scarcity.