Complex sentence: The book is an amalgam of material from Wooden Leg along with support and corroboration from many contributors, including most of the seventeen Northern Cheyenne participants of the Battle of the Little Big Horn still alive at the time of the interviews.
Split into simpler sentences: The book is an amalgam of material from Wooden Leg along with support and corroboration from many contributors. Amongst these contributors were most of the seventeen Northern Cheyenne participants of the Battle of the Little Big Horn still alive at the time of the interviews.