1. University of Massachusetts, Amherst, MA, USA.
2. Cornell University, Ithaca, NY, USA.
3. Center for Agricultural and Rural Development, Iowa State University, Ames, IA, USA.
4. University of Texas, Austin, TX, USA.
5. Resources for the Future, Washington, DC, USA.
6. Virginia Tech, Blacksburg, VA, USA.
7. University of Houston, Houston, TX, USA.
8. University of Minnesota, Minneapolis, MN, USA.
9. University of Wisconsin, Madison, WI, USA.
10. University of California, Berkeley, CA, USA.
11. National Bureau of Economic Research, Cambridge, MA, USA.
12. University of Virginia, Charlottesville, VA, USA.