Rensberry.com
This book was recommended to me by a doctor who I respect immensely and who knows more about the 7th CAV than anyone else I know in person. I was drawn to it as he told me it was incredibly well researched and probably as accurate as any book out there right now. He also said it talked about some of the doctors who served in the same unit.
This book was everything he said and more. I am now fascinated by Custer, have new-found respect for the Cavalry of old, and appreciate the history of the unit I have served in for the past 2 years. This book demonstrates how the last stand was mutually acted by both Custer and Sitting Bull. Read it to learn what I mean ;)
I highly recommend this book to all interested in history of the United States.