Renowned historian Stephen Ambrose offers up another chapter in the story of America in this portrait of two powerful men. He parallels the life of Crazy Horse, the great leader of the Oglala Sioux, with that of General George Armstrong Custer, the man he defeated at the battle of Little Bighorn. It is a balanced, highly readable account, that serves to shed light on the similarities between these antagonistic men.  (USW136, $17.00)