Glenn Shafer Amos Tversky Languages and Designs for Probability Judgment. 345-374 2008 Classic Works of the Dempster-Shafer Theory of Belief Functions http://dx.doi.org/10.1007/978-3-540-44792-4_13 series/sfsc/2008-219 db/series/sfsc/sfsc219.html#ShaferT08