Roy W Jastram, a professor of Business Administration at the University of California-Berkeley wrote a comprehensive book on gold in 1977, called The Golden Constant. It is widely available. In the course of his research and writing the book, he became interested in the story of Silver as a Monetary Metal. In 1981 he wrote Silver: The Restless Metal. This book is hard to find and is currently out of print. Here is a link to a pdf scanned copy of the book. It is good reading, and a resource to learn about he monetary history of Silver and its Boom and Bust existence throughout history.