"The Big Cave: Early History and Authentic Facts Concerning the History and Discovery of the World Famous Carlsbad Caverns of New Mexico" by Joe N. Long and Abijah Long is a history of the discovery of Carlsbad Cavern. It's taken from the writings of its, at the time, modern day discoverer, along with a discussion of the geologic processes which caused its formation and an introduction to the Caves as a visitor would find them today.