Confession Concerning Christ's Supper
Confession Concerning Christ's Supper (1528) (German: Vom Abendmahl Christi, Bekenntnis) is a theological treatise written by Martin Luther affirming the Real Presence of the body and blood of Christ in the Eucharist, defining Luther's position as the sacramental union. Notable among its respondents were Huldrych Zwingli and Johannes Oecolampadius, who denied the Real Presence.
Source: Wikipedia — Confession Concerning Christ's Supper (CC BY-SA 4.0)