Oxford Research Encyclopedia of Religion (Online) by editor in chief, John Barton A peer-reviewed resource that includes the formerly titled Oxford Encyclopedia of Martin Luther.

The Oxford Dictionary of the Christian Church (Online) by Andrew Louth (editor) 6,000 cross-referenced A-Z entries from theology; churches and denominations; patristic scholarship; and the bible; to the church calendar and its organisation; popes; archbishops; saints; and mystics. Online available. Newly updated in 2022.

Encyclopedia of Christianity by John Bowden (Editor) A one-volume encyclopedia dedicated Christianity on a global scale. Includes many entries on the Reformation era.