1. ASCE (American Society of Civil Engineers) 1999 Optimization of Collection System Maintenance Frequencies and System Performance Washington
2. ASCE 2008 Resource Guide to the Colorado Infrastructure Report Card http://colo-radoasce.org/misc/2008Report.pdf
3. Anderson , R.F. 2010 Trends in Local Government Expenditures on Public Water and Wastewater Service and Infrastructure: Past, Present, and Future The US Conference of Mayors-Mayors Water Council Washington
4. A Game Plan for Aging Water Infrastructure;Baird;Jour. AWWA,2010