A Tale of a Tub
The "Tale" was originally published in 1704 by John Nutt. Swift had used Benjamin Tooke previously when publishing for Sir William Temple. He would use Tooke for both the fifth edition of the "Tale" (1710) and later works. Tooke's successor, Benjamin Motte, published Swift's "Gulliver's Travels". This difference in printer is only one of the things that led to debate over authorship of the work.
A Swiftly Tilting Planet
Matthew Maddox's second novel, "The Horn of Joy" (1868), serves as a MacGuffin in "A Swiftly Tilting Planet". Charles Wallace spends a significant portion of the book trying to remember or discover what Maddox wrote in it, or to reach Maddox himself. Readers sometimes wonder whether "The Horn of Joy" ever existed; but it is a fictional book, created by L'Engle. Polly O'Keefe finds a copy of "The Horn of Joy" in her room (formerly Charles Wallace's room) when she visits her grandparents in "An Acceptable Time". Maddox's equally fictional first novel, "Once More United", is said to have been published in 1865.