There isn't much better information than the AWS codes. I would recommend the AWS D1.1 code and the AWS A2.4, Standard Symbold for Welding, Brazing, and Nondestructive Examination. I also have a book, Design of Welded Structures, that gives a structural engineer most of what he might need to understand how to size a weld. Finally, on a more academic level, I have a book titled Welding Inspection Technology. I don't know what these books cost these days, but I think the AWS D1.1 is pretty high (~$300). The other books should be substantially less.