Logos doesn't have many contemporary, exegetical resources on union with Christ. (In fact I only found one through a search). But it's an important area of study that effects other areas of theology like atonement.
https://suggestbooks.uservoice.com/forums/308269-book-suggestions/suggestions/36394261-covenant-salvation-union-with-christ-by-michael
This one is on Faithlife eBooks and I highly recommend it! https://ebooks.faithlife.com/products/65480/union-with-christ-the-way-to-know-and-enjoy-god
Thanks for pointing this out. I picked it up just now. However, I would like to have a more in-depth treatment like the on provided by Horton.
