These books, "The Harp of God" and Deliverance" by J.F. Rutherford were published in 1921 and 1926 respectively. Rutherford was the 2nd President of the Watch Tower Bible & Tract Society and was a prominent leader of the Jehovah's Witnesses.
Harp of God (1921) is a beginner's text designed to outline fundamental biblical teachings of the Watch Tower movement. 381 pages including the index.
Deliverance (1926) is a theological exploration of redemption, the fall of "evil organizations" and restoration of a theocratic world order.
379 pages including the index.