2003
Public Policy Institute, The Urban Institute, 2003
2002
Eric Toder, Lawrence Thompson, Melissa Favreault, Richard Johnson, Kevin Perese, Caroline Ratcliffe, Karen Smith, Cori Uccello, Timothy Waidmann, Jillian Berk, Romina Woldemariam, Gary Burtless, Claudia Sahm, Douglas Wolf Urban Institute Research Report, The Urban Institute, 2002