Prof. Murray Seligman is, without doubt, one of the leaders and founders of contemporary Positive Psychology. This website contains a number of good resources, including papers and interviews.
Site gives an overview of Structured Modeling, and compares it to other management models.
http://www.anderson.ucla.edu/faculty/art.geoffrion/home/csts/index.htm
These studies have more of a focus on negotiations from an international conflict standpoint, but I felt that they were of such high quality, they merited entry.
http://www.law.stanford.edu/program/centers/scicn/#scicn_papers
I know it doesn’t sound business related, but I found these notes on negotiations at Los Alamos National Labs, and thought they had some value beyond the original topic.