Effective Prayer - (Classic Booklet) - CBS by C H Spurgeon and published by Classics.
Concerning prayer Spurgeon wrote "Prayer itself is an art which only the Holy Ghost can teach us. He is the giver of all prayer. Pray for prayer - pray till you can pray." This booklet, from which the above quote is taken from, is the complete sermon originally entitled "Order and Argument in Prayer" which is based on a text from Job 23: 3 & 4