Book excerpt: When L. Frank Baum introduced Dorothy and friends to the American public in 1900, The Wonderful Wizard of Oz became an instant, bestselling hit. Today the whimsical tale remains a cultural phenomenon that continues to spawn wildly popular books, movies, and musicals. Now, editors John Joseph Adams and Douglas Cohen have brought together leading fantasy writers such as Orson Scott Card and Jane Yolen to create the ultimate anthology for Oz fans.