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.
Gordon’s Quiet Talks on the Crowned Christ of Revelation looks forward to the end times with meditations for our consideration.
Teasley Holy Spirit and Other Spirits is about the Holy Spirit’s effect on the believer as wells as how other spirits (demons) try to affect mankind with specific unholy spirits.
Steele – Love Enthroned is a work on what is love, its different aspects, biblical examples, etc. 23 chs.
In Smeaton – The Doctrine of the Holy Spirit he examines historically what the Bible teaches about the Holy Spirit. This is an old classic work (1862). In the New Testament portion he looks at topics.
Aitken Doctrine of Baptism is a 8 chapter work on baptism, looking at it from the consideration of Regeneration and Conversion.
Biderwolf-A Help to the Study of the Holy Spirit surveys, names of the Spirit, advent, personality, deity, sealing by, anointing of, fruits, baptism of, filling of, emblems, resistance of the Spirit.