Cox, David – Understanding the Bible Doctrine of the Trinity

Cox details the evidence for the doctrine of the Trinity in the Bible looking dozens of different angles.

Anon – Basic Christian Doctrine

Anon Basic Christian Doctrine is a 50 Chapter doctrines book that is anonymous.

Shaw Of God and the Holy 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.

Wiley Systematic Theology 3 vols

Henry Orton Wiley’s 3 vol Christian Theology work has 40+ chapters on the different areas of theology, such as, Bibliology, Theology Proper, etc.

Gill, John – A Body of Doctrinal Divinity, Books 1 -7

A doctrinal book Body of Doctrinal Divinity is a set of 7 doctrinal books by Reformed John Gill.