@PhdThesis{hoffmann-1996a,
  author         = {Jean Robert Hoffmann},
  title          = {The Ecology of Cooperation},
  year           = {1996},
  month          = {Sep},
  note           = {Thesis is series of Adobe PDF files in a directory},
  school         = {University of East Anglia},
  key            = {hoffmann-1996a}
}