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<p>Are you ISBNs for individual books or packages? If it’s for packages, it won’t work on Amazon or Half because it’s an ISBN that the Pitt Bookstore has assigned. Other than that, the numbers should work for the websites. If they don’t, search by author and year. </p>
<p>If you can’t find books by ISBN, use author name, book title, and publishing year.</p>
<p>Generally publishing year DOES matter, because the content of the book, the questions, and the ordering of the questions, among other things, change from publication to publication. If you are still curious, though, you can always email your professor and ask if it matters.</p>