Fox's Book of Martyrs - John Foxe
Patrick and the Early Celtic Church - Brian Hoeck
The Sabbath Keepers of Transylvania - D Thomas Lancaster
Sabbatarians in Transylvania - Gerhard O. Marx
A History of the True Church Traced from 33 A.D. to Date - Andrew N. Dugger and Clarence O. Dodd, 1972
History of the Seventh Day Church of God, Volume I - Richard C. Nickels, 1999
History of the Seventh Day Church of God, Volume II - Compiled by Richard C. Nickels, 1973
Truth Triumphant: The Church in the Wilderness - Benjamin George Wilkinson, PH. D.
The Incredible History of God's True Church - Ivor Fletcher