It hard to understand covenant and covenants in the bible and Ancient Near East without this book. Kingdom Prologue is also great.

I studied with him before he retired. He is in glory now. Dr. Kline is the greatest OT Theologian of the 20th Century. He is not well known, but drink deep from his books. No one will ever be able to refute his covenantal interpretation of Deuteronomy. They never have. This is not Christianity-lite. Google his name to find some of his lectures online for free.