Claim: Youth and the Bright Medusa, a book by Willa Cather, was published by Alfred A. Knopf while Cather was still under contract with Houghton Mifflin.
Evidence: The book was the first book Cather published with Alfred A. Knopf. Since Cather was still under contract with Houghton Mifflin for her novels, Knopf published her short story collection, Youth and the Bright Medusa and advertised the collection in the New Republic.