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.
Anderson Silence of God theodicy is about when God is silent, the silence of God, which in theology it is theodicy. Why doesn’t God immediately vindicate his children.
Arminius On The Sin Against the Holy Spirit is a single chapter work on this issue by James Arminius.
John Owen – Decay of Spiritual Affections is a 12 page sermon apparently from a larger book of sermons (starts on page 250+).
De Spiritu Sancto (Basil) is an old work by the Church Fathers, 30 chs. which discusses the Holy Spirit in relationship to the Trinity.
Winslow in Christ and the Christian in Temptation examines how Satan tricks the Christian into falling into sinful conduct. These elements are the keys by which Satan tricks us.
Steele – Love Enthroned is a work on what is love, its different aspects, biblical examples, etc. 23 chs.