It's from Interweave Editors and can be purchased on Amazon!
I got it as a gift when my knitting mother-in-law discovered I'm a huge fan of the books (and now the show. :) ) Apparently you can also buy kits with the patterns and the recommended yarns.
So I did some looking and it looks like Lion Brand (who did the official licensed knits) has broken links. I found this book on amazon though that’s inspired by the series that looks pretty good.
https://www.amazon.com/Highland-Knits-Knitwear-Inspired-Outlander/dp/1632504596