First, you notice that all of the front-facing books are in groups that are alphabetical order...except one that seems very out of place:
The Siren by Tiffany Reisz is terribly out of place, and totally in the wrong section of the bookstore. Or extra resourcefulness points if you image-search this photo to find the right book.
Now, looking at the clue, you realize that the first letters of the first four quoted words are: ISBN. So you’re looking for an ISBN number.
Then, in the second part of the clue, you find that there are 13 books in the Series of Unfortunate Events Collection, so you must be looking for and ISBN-13 code instead of an ISB-10. So, doing a search gives you your answer: 9780778313533