Two good recent books on Custer and the battle - A Terrible Glory by James Donovan, and The Last Stand by Nathaniel Philbrick.
You do know that the problem with books and their revision of history is not always accurate? I’m not really sure what happened here...and probably never will. Factual accounts seem to go by the wayside... You have to believe what you want to by reading several accounts of the action.
It is really a shame that our education system (including the publication of books) has become so inaccurate or just plain false... Sign of the times I suppose...