The book "Jordens väktare" is not a book in the Jacob Colt series. It's part of the same universe, since a character from some earlier books in the Colt series is in this book under a different name (Dean; yet clues make it obvious that this is the Silfverbielke character from other books before and after this book).
Listing it as part of the Silfverbielke series is more accurate, even though that would be a spoiler of sorts and would still not be as accurate as letting this title be a standalone title in the Colt/Silfverbielke universe.
Listing it as part of the Silfverbielke series is more accurate, even though that would be a spoiler of sorts and would still not be as accurate as letting this title be a standalone title in the Colt/Silfverbielke universe.