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.
The bible of dog books. All you ever wanted to know about the different breeds, plus some useful information about everything else (history, food etc.)
I knew everything about every breed by the time I was 8. I still can recite parts of the descriptions by heart.
Can you tell that I REALLY REALLY wanted a dog when I was eight? ;-)