|A214 : by Paul Henebury
Obviously, the first place must be the Bible. I don't say that to be a smart-Alec; I truly believe we must let the Bible itself define what a biblical covenant is.
As to other helpful books:
Articles on 'covenant' in the standard reference works: ISBEi, etc.
If I may include my series Christ at the Centerj (which I am falteringly trying to make into an e-book), that will give you a basic idea of where I'm coming from.
I should tell you that I do not agree with any of the sources I list completely. One of the real problems with studying the subject is the often contradictory things people say. They will stress the ANE background, and will cite "parallel" examples, which must mean what they say, and then they will often reinterpret the provisions of the covenants under the influence of their view of the NT! Reformed writers are particularly bad for this (e.g. Michael Horton, God of Promisek).
God bless you and yours.