Anyone who regularly tackles challenging crossword puzzles will be familiar with the frustration of unanswered clues blocking the road to completion. This volume provides the ultimate aid for tracking down those final solutions.
Books can be attributed to "Unknown" when the author or editor (as applicable) is not known and cannot be discovered. If at all possible, list at least one actual author or editor for a book instead of using "Unknown".
Books whose authorship is purposefully withheld should be attributed instead to Anonymous.