What are the best books for improving calculation skills as opposed to spotting tactics?

Obviously this question is rating dependent. Perhaps these books would be aimed at one of: 1800 - 2000 - 2200 - 2400. Some books are obviously more general, but have good sections on calculation (for example Jon Tisdal's, Improve Your Chess Now).

Jacob Aagaard - Grandmaster Preparation: Calculation

Certainly one that is highly recommended, but obviously it is considered to be very challenging, so...What rating level do you think is a minimum entry point? Any ideas about books that might be more accessible to lower rated players?

Honestly, I don't know. You could also try the harder puzzles in something like Woodpecker Method, but Aagaard's book still seems like a good try. But you're 2000 in rapid, so I feel like the Aagaard book, if used appropriately, shouldn't be bad. I'm using it, myself.

The key is not to try solving each puzzle like a tactics book. Set up the position, set a timer for 20 minutes, and then try to calculate the winning variation all the way through -- don't just make guesses at it. At the end of 20 minutes, write down the variation that you're going with, and then compare that variation with the line that Aagaard (or whoever) gives. Based off of that, you should be able to determine the weak points in your calculation (forgetting that pieces leave squares undefended, not looking at all candidate moves, not calculating through to the end of a position) and then adjust accordingly.

But if you're looking for different books, unfortunately, I won't know them myself.

This method also works for just a standard book of annotated games, btw. Playing through a game, seeing a diagrammed position, and then pausing and thinking for 20 minutes what the best move would be, calculated all the way through, and then comparing that move to the annotation.

This method, btw, was adopted from Jonathan Rowson's Chess for Zebras (which just got a reprint a few months ago!). So if you're interested specifically in the ins and outs of this method, I would check out that book.

Probably you would like to check out the books by Artur Yusupov. 

Thanks for those ideas - they make a lot of sense! O have worked through puzzles 1- 549 in the Woodpecker Method. It is an excellent book for tactical training, but almost always with one clear line. The Aagaard book sounds like exactly what I need. 

Thanks you so much for taking the time to write these comments - much appreciated!

I believe Aagard is too hard. Even for me (2028 FIDE, 2072 next month) like I can often solve the puzzles but it takes too much time. Woodpecker is way better. 

"Think Like a Grandmaster" - Kotov
Example:
https://www.chessgames.com/perl/chessgame?gid=1084375 

That was my first thought too. I guess what I am looking for is a book that develops calculation in positions where there isn't a clear "puzzle" to solve.

I have read this, but I want a book with more examples.