St. Augustine of Hippo 
Saint Augustine’s Anti-Pelagian Writings [EPUB ebook] 

This edition contains the following writings:
Contents:

On the Merits and Forgiveness of Sins, and on the Baptism of Infants
On the Spirit and the Letter
On Nature and Grace, Against Pelagius
Concerning Man’s Perfection in Righteousness
On the Proceedings of Pelagius,
A Treatise on the Grace of Christ, and on Original Sin
On Marriage and Concupiscence.
On the Soul and Its Origin
A Treatise Against Two Letters of the Pelagians
A Treatise on Grace and Free Will.
Treatise on Rebuke and Grace
A Treatise on the Predestination of the Saints,
A Treatise on the Gift of Perseverance, Being the Second Book