Introductory Materials
General Introduction
Chapter 13 in A Historical Introduction to the New Testament (New York: Harper & Row, 1963), reproduced on Religion-Online. (You will have to scroll down for the section specifically on Galatians.)
Chapter 18 in An Introduction to the New Testament (New York: Harper & Brothers, 1950), reproduced on Religion-Online. (You will have to scroll down for the section specifically on Galatians.)
An element among the on-line course materials for The New Testament and Its Context at Atlantic Baptist University.
Helpful introductory article (at The Biblical Studies Foundation).
In the Catholic Encyclopaedia (1909). [Note: old-fashioned]
Specific Issues
If you wish to learn more, F.F. Bruce has written a useful series of articles discussing many of the specific issues in the interpretation of Galatians (these are in PDF format):
Bulletin of the John Rylands Library 51.2 (1969): 292-309.
Bulletin of the John Rylands Library 52.2 (1970): 243-266.
Bulletin of the John Rylands Library 53.2 (1971): 253-271.
Bulletin of the John Rylands Library 54.2 (1972): 250-267.
Bulletin of the John Rylands Library 55.2 (1973): 264-284.
