CARM-Seventh Day Adventist by Matt Slick is a series of pages on this group as well as their version of Scripture, a Clear Word version.
This is a 17 page examination and defense of the doctrine of the Trinity. Alford examines Christ’s humanity as well as his divinity. Specifically Alford establishes Christ’s divine traits (omniscience, wisdom, omnipresence, immutability, omnipotence, equality with the Father, deity), and then he examines issues of the trinity, plurality of the Godhead, number of persons in the Godhead, the Father-Son-Spirit are one God. Then Alford examines the consequences of this doctrine, specifically in the light of the Unitarian’s denial of it, and finally Alford examines criticisms of the Trinity.
Robert Shaw’s short 1 chapter work on God and the Holy Trinity is an excellent collection of observations and verses that defend the Trinity.
Another Gordon Quiet Talks series about those who win against the world, and winning forces, Jesus, Holy Spirit, etc.
Warfield Person and Work of the Holy Spirit is a 15 chapter work on various central elements of the doctrine of the Holy Spirit.
Berry Adventures in the Land of Canaan is a devotional work about Israel entering into the promised land as a parallel to our spiritual warfare towards our sanctification.
John Owen – Decay of Spiritual Affections is a 12 page sermon apparently from a larger book of sermons (starts on page 250+).