The answer is 42 (sorry couldn't resist!
)
Mayhap you could include in the book title that it is an anthology (Ultimate Hitchhiker's Guide, Books 1-5). You could also create a custom column that would list the titles in an anthology. If you leave the Book Details panel up all the time, you could list the individual titles there (I would do the first and third suggestions myself since I do leave the Book Details panel up at all times).