  [Note: This bibliography contains only items referred to in the notes and a few other selected items of interest. For a general introduction to some of the main historical and philosophical issues surrounding relations, see Heil 2009 and Marmodoro and Yates 2016. For discussion of specifically medieval theories, as well as further bibliographical references, see Brower 2016, Henninger 1989, Marenbon 2016, Olson 1987, Penner 2016, and Weinberg 1965. For more contemporary defenses of the view we have been calling ‘realism without polyadic properties,’ see Campbell 1990, Fisk 1973, Mulligan 1998, Parsons 2008, and Schaffer 2010.]