O Lord, I Seek Your Countenance Explorations and Discoveries in Pope Benedict XVI's Theology Gaal, Emery de Innbundet / 2018 / Engelsk
John Henry Newman and Joseph Ratzinger A Theological Encounter Gaal, Emery de Innbundet / 2025 / Engelsk
Joseph Ratzinger and the Healing of the Reformation-Era Divisions Gaal, Emery de Innbundet / 2019 / Engelsk
