Topical

E.P. Sanders - Paul and Palestinian JudaismThis is a work that kicked off the New Perspective on Paul. Sanders goes into extra-biblical material from Judaism to help us understand how the Jews viewed their own religion. Rather than imposing Luther back on the Torah, this book advises letting Judaism speak for itself. This allows you to read the Torah and the Old Testament with new ears with a greater degree of accuracy. This book has been challenged in several areas but still stands as an important reference work by its own right. There are other works that are shorter and have the benefit of another few decades of scholarship like the next book.

Commentaries

F.F. Bruce - The Epistle to the Galatians (New International Greek Commentary)Highly technical. This works off of the Greek text rather than the English text so you better have brushed up on your Greek!Hans Betz - Galatians (Hermeneia)This is an excellent commentary on Galatians but does require some knowledge of Greek to get the full use out of it.James Dunn - Galatians (Black's New Testament Commentary)Requires less knowledge of Greek and also incorporates information from the New Perspective on Paul that is very helpful. This is commentary is one of my favorites that I would recommend to anyone wanting a better grasp on Galatians.Ronald Fung - The Epistle to the Galatians (New International Commentary on the New Testament)I haven't used this one. I list it because of my respect for the NICNT.Scot McKnight - Galatians (NIV Application Commentary)I have used McKnight and this is the perfect commentary for an introduction to Galatians. He is influenced by E.P. Sanders and James Dunn on the New Perspective and I view that as a plus.Ben Witherington - Grace in Galatia: A Socio-Rhetorical CommentaryI haven't consulted this commentary yet so I am not sure how good it is. I mention it here because I have used BWIII a lot on other studies and respect his work. It is typically very readable with lots of detail but still written well enough that most people would find it helpful.Tom Wright - Paul for Everyone: Galatians and ThessaloniansAs I have said before these are great to give you the overview but less helpful if you are looking for answers to specific textual questions. I use these any time I am studying a particular book of the New Testament.

Articles

N.T. Wright - Paul, Arabia, and Elijah (Galatians 1:17)N.T. Wright - The Letter to the Galatians: Exegesis and Theology