Swedish Carving Techniques by Wille Sundqvist is the book on this type of carving. I checked it out a few times from the local library several years ago, and then it disappeared from their inventory. It would be cool if Taunton would reprint it, or let someone else do so because at the price it’s going for on the used market now, it is inaccessible to me.
I’ve supported, and am very excited about this kickstarter project to document Wille and his work.
I should also mention that Wille’s son, Jogge, has a DVD out which I have not yet seen.