This term I've spent some time studying nonmonotonic logics. This lead me to look at David Makinson's work. Makinson has done a lot of work in this area and he has a nice selection of articles available on his website. One unexpected find on his page was a paper called "Completeness Theorems, Representation Theorems: What’s the Difference?" A while back I had posted a question about representation theorems. In the comments, Greg Restall answered in detail. Makinson's paper elaborates this some. He says that representation theorems are a generalization of completeness theorems, although I don't remember why they were billed as such. There are several papers on nonmonotonic logic available there. "Bridges between classical and nonmonotonic logic" is a short paper demystifying some of the main ideas behind non-monotonic logic. The paper “How to go nonmonotonic” is a handbook article that goes into more detail and develops the nonmonotonic ideas more. Makinson has a new book on nonmonotonic logic, but it looked like most of the content, minus exercises, is already available in the handbook article online.