On a recent forum post about recommendations for books on the Trinity Carl Sanders, the m.Ed lecturer in Theology came up with a couple of suggestions that his students find helpful. They are published by Crossway and IVP respectively.
My students have really enjoyed Fred Sanders' The Deep Things of God (he is not a relative, if you're interested) and Michael Reeves' Delighting in the Trinity. They're both quite good - though not free...and not, as far as I can tell yet on Logos.
