It will soon be two years since 13-digit ISBNs were introduced. Because some of you have used systems that haven't been updated, we've included 10-digit ISBNs in our listings of titles. But ISBN scouts report this should no longer be an issue, so in the new year, we are planning to include only 13-digit ISBNs in Shelf Awareness.
If this is a problem, speak now or forever hold your 10-digit peace!