Prayer

• Oh, that you would leave off objecting, and fall upon praying. by Thomas Brooks
• The Holy Spirit and your praying. by Thomas Brooks
• The Most High A Prayer-Hearing God by Jonathan Edwards.
• John Murray: Man of Prayer by Edmund P. Clowney (off-site).
• The Sovereignty of God and Prayer by John Piper.
• The Hidden Life of Prayer A great booklet by David M'Intyre.
• The Way of Salvation: Prayer Thomas Watson on prayer.
• A Call to Prayer by J. C. Ryle

• I'd also recommend The Puritans on Prayer published by Soli Deo Gloria located at Ligonier Ministries.