History of the Christian Church: St. Paschasius Radbertus
- Biographical article by Philip Schaff on the monk famous for his views on the Eucharist.
- http://www.ccel.org/ccel/schaff/hcc4.i.xiv.xxxii.html

The Theory of Paschasius Radbertus
- An outline of the theologian's understanding of the manner of Christ's presence in the sacrament of the Eucharist.
- http://www.ccel.org/ccel/schaff/hcc4.i.xi.xxi.html

St. Radbertus
- Short biography of this monk, for children.
- http://www.tntt.org/vni/tlieu/saints/St0426.htm

Catholic Encyclopedia: St. Paschasius Radbertus
- Biographical article on the deacon, Benedictine abbot, and theologian, who died in 860.
- http://www.newadvent.org/cathen/11518a.htm