It's on Amazon with no less than 1,125 ratings:
https://www.amazon.com/Heart-Everything-That-Untold-American-ebook/dp/B00BSAZ614
The authors are not historians, more journalists:
https://www.amazon.com/Tom-Clavin/e/B0039STC40/
https://www.amazon.com/Bob-Drury/e/B001IXM7AE/
Here is a 2014 review by Four Arrows, Fielding Graduate University:
The Heart of Everything That Isn’t
The Untold Story of Anti-Indianism in Drury and Clavin’s Book on Red Cloud
https://thestringer.com.au/the-heart-of-everything-that-isnt-the-untold-story-of-anti-indianism-in-drury-and-clavins-book-on-red-cloud-2-8524
Later reprinted here:
https://newsmaven.io/indiancountrytoday/archive/the-heart-of-everything-that-isn-t-the-untold-story-of-anti-indianism-RpzVJ-ZGE0q3wlmbZ-4vzQ/
https://www.researchgate.net/publication/288183626_The_Heart_of_Everything_That_Isn't
Here is a review of an adapted version. It starts thus:
Friday, May 26, 2017
Not Recommended: THE HEART OF EVERYTHING THAT IS: THE UNTOLD STORY OF RED CLOUD, AN AMERICAN LEGEND by Bob Drury and Tom Clavin (adapted by Kate Waters)
In 2013, Simon and Schuster published The Heart of Everything That Is: The Untold Story of Red Cloud, An American Legend. White people loved it. They bought it. They praised it. It became a New York Times Bestseller. White people love The White Man's Indian.
And so--unsurprisingly--Simon and Schuster decided they ought to make it available to young people, too. The "young readers edition" came out in February of 2017 from Margaret K. McElderry Books. It was adapted for young readers by Kate Waters.
(An aside: as I write this post, I throw down snark--and then delete it--again and again.)
(https://3.bp.blogspot.com/--ygb6UOoiLY/WSgp5waOZUI/AAAAAAABj_M/O4vpE4JbqYM3k6i1sXmZlivdIHuICJhHQCLcB/s1600/Screen%2BShot%2B2017-05-26%2Bat%2B8.12.38%2BAM.png)