2011 U.S. Government report on the challenges facing the Social Security system and its ability to meet its obligations to retirees and those on disability.

2011 report by the Congressional Research Service on expenditures for conflicts and terrorism-related operations since 2001.

2011 study for the National Bureau of Economic research on high levels of public debt and the consequences.

2008 study published in the Journal of Economic Perspectives on the factors that have hurt the U.S. pension-insurance corporation.

2010 study exploring the relationship between spending on non-drug medical services and pharmaceutical expenses across geographical regions.

2009 RAND Corporation paper examines the potential benefits of workers remaining in the workforce for longer periods of time.

2010 study by Stanford and Singapore Management University on the effect of credit tightening on international trade during the 2008-2009 financial crisis.

2006 study by California State University, Sacramento, on how state budgeting changed after the enactment of Proposition 13.

2009 University of Pennsylvania Law School research paper looking at the trade-offs between the two options.