Puritan Paperbacks in the public domain already available on Monergism in eBook formats. 

Two Paperbacks are original works, and not in the public domain, those are "A Puritan Golden Treasury," and "All things made New" by John Flavel. Those cannot be made into eBooks. 

• The Incomparableness of God  by George Swinnock
• An Ark for All God’s Noahs by Thomas Brooks
• Select Practical Writings of Robert Traill
• Searching Our Hearts in Perilous Times by John Owen
• A Treatise on the Fear of God by John Bunyan
• Flowers From a Puritan’s Garden by C. H. Spurgeon
• Duties of Christian Fellowship by John Owen
• All Things Made New by John Flavel
• The Way to True Peace and Rest by Robert Bruce
• The Crook in the Lot by Thomas Boston
• A Heavenly Conference by Richard Sibbes
• The Glorious Feast of the Gospel by Richard Sibbes
• A Lifting Up for the Downcast by William Bridge
• Christ Set Forth by Thomas Goodwin
• The Golden Treasury of Puritan Quotations by I.D.E. Thomas
• A Sure Guide to Heaven: An Alarm to the Unconverted by Joseph Alliene
• All Loves Excelling by John Bunyan 
• All Things for Good by Thomas Watson
• Apostasy from the Gospel by John Owen
• The Art of Prophesying by William Perkins
• A Treatise of Christian Love by Hugh Binning
• The Christian’s Great Interest by William Guthrie
• Come and Welcome to Jesus Christ by John Bunyan
• Communion With God by John Owen
• The Doctrine of Repentance by Thomas Watson
• Dying Thoughts by Richard Baxter
• Facing Grief: A Token for Mourners by John Flavel
• Preparations for Suffering by John Flavel
• Glorious Freedom: The Excellency of the Law Above the Gospel by Richard Sibbes
• The Glory of Christ by John Owen
• The Heart of Christ in Heaven Towards Sinners on Earth by Thomas Goodwin
• Heaven on Earth: A Treatise on Assurance by Thomas Brooks
• Indwelling Sin in Believers by John Owen   
• The Jerusalem Sinner Saved by John Bunyan
• Josiah’s Reformation by Richard Sibbes
• Justification Vindicated by Robert Traill
• Learning in Christ’s School by Ralph Venning
• Letters of Samuel Rutherford
• The Love of Christ by Richard Sibbes
• The Mortification of Sin by John Owen
• The Mystery of Providence by John Flavel
• Prayer by John Bunyan
• Precious Remedies Against Satan’s Devices by Thomas Brooks   
• The Rare Jewel of Christian Contentment by Jeremiah Burroughs
• The Secret Key to Heaven by Thomas Brooks   
• The Spirit and the Church by John Owen
• Spiritual-Mindedness by John Owen
• Temptation Resisted and Repulsed by John Owen
• The Acceptable Sacrifice by John Bunyan
• The Bruised Reed by Richard Sibbes
• The Godly Man’s Picture by Thomas Watson   
• The Great Gain of Godliness by Thomas Watson
• The Holy Spirit by John Owen
• The Lord’s Supper by Thomas Watson
• The Reformed Pastor by Richard Baxter
• The Shorter Catechism Explained from Scripture by Thomas Vincent
• The Sinfulness of Sin by Ralph Venning 
• The True Bounds of Christian Freedom by Samuel Bolton
• Smooth Stones from Ancient Brooks by Thomas Brooks
• Sermons of the Great Ejection by Varioous Puritans