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.
A delightful overview of America's most famous detective. I am struck at how Chester Gould foretold technology that many recognize today. Additionally, his bold, high-contrast artwork enhanced the stories and made 'Dick Tracy' a favorite of all ages.
This book does a good job of covering the history of the comic. Today's Marvel and DC fans might take a look at this to see what others in the field were able to accomplish in the daily newspapers.