1. C.F. Tiffany, J.P. Gallagher, and C.A. Babish IV, Aeronautical Systems Center, Engineering Directorate, Wright-Patterson Air Force Base, ASC-TR-2010-5002.
2. FAA-2010-1280-001, Federal Register, 76, 6 (2011).
3. FAA AC No: 120-104, 01/01/2011.
4. S.L. Davis, K. DeGood, N. Donohue, and D. Goldberg, Transportation for America (2013) http://t4america.org/docs/bridgereport2013/2013BridgeReport.pdf .
5. http://www.railwayage.com/index.php/mechanical/freight-cars/ttci-rd-how-healthy-are-your-castings.html .