What was the family background and childhood of James Buchanan like?What jobs did he have? Where did he go to school? Where did he live? Who were his all-time friends?
I think you would be very interested in a work by the notable author John Updike. The title is Buchanan Dying. It is a three-act "closet drama" (not meant to be staged). In this drama James Buchanan is lying in bed and is visited in his imagination by many of the most important people from his past life. It shouldn't be hard to get the book from a good library, since John Updike was such a prominent writer. He was extremely interested in Buchanan (like yourself, apparently), so he must have written other things about him such as essays and reviews. I can't give you other titles, although I did read Buchanan Dying a long time ago and can recommend it highly for your purposes if you aren't already familiar with it. Please refer to the links below.