1. American Association of State Highway and Transportation Officials. (2007). Transportation: Invest in our future. Available at http://financecommission.dot.gov/Documents/Background%20Documents/tif2-1.pdf
2. American Society of Civil Engineers. (2013). Report card for America's infrastructure, 2013. Available at www.infrastructurereportcard.org/a/#p/grade-sheet/gpa
3. State and local debt burdens in the 1980s: A study in contrast;R. Bahl;Public Administration Review,1993
4. Public-private partnerships: Balancing financial returns, risks, and roles of the partners;F. Becker;Public Performance & Management Review,2005