Gospel of the Comforter by Steele is a 36 chapter work on the Holy Spirit and different aspects of Him (1897).
The Carnal Mind by Harmon Allen Baldwin is a 30 chapter work on the carnal mind, defining terms, biblical view, what is evil, guilt, pollution, self-denial, oppositon to light, etc.
Aitken Doctrine of Baptism is a 8 chapter work on baptism, looking at it from the consideration of Regeneration and Conversion.
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.
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.