My Sacred Harp history book Songs Before Unknown became available in November 2015. It is now also available in an e-book. Singer and typesetter Karen Willard has prepared a version that is "a fully text searchable e-book suitable for kindles, iPads, and other tablets."
I'm an "old-school" book person myself. I don't use or understand all that much about the e-books. But I know many people today prefer the advantages they find in e-books. This electronic version can be especially good for singers overseas. Postage costs to get the hard copy shipped to them are extremely costly. The e-book will sell for $10, which is a $5 savings over the hard copy, plus saving postage. If are interested, you can e-mail me for more information: firstname.lastname@example.org .