1. Brunner, E., Suter, M.: International CIIP Handbook 2008/2009: An Inventory of 25 National and 7 International Critical Infrastructure Protection Policies. Center for Security Studies, ETH Zurich, Switzerland (2008)
2. Transportation Security Administration: Critical Infrastructure and Key Resources Sector-Specific Plan as input to the National Infrastructure Protection Plan. Dept. of Homeland Security, USA (2007)
3. Theoharidou, M., Kotzanikolaou, P., Gritzalis, D.: Risk-based criticality analysis. In: Palmer, C., Shenoi, S. (eds.) 3rd IFIP Int. Conf. on Critical Infrastructure Protection (CIP 2009), pp. 35–49. Springer, USA (2009)
4. European Council: Directive 2008/114/EC on the identification and designation of European critical infrastructures and the assessment of the need to improve their protection. Official Journal L345, pp. 75–82 (2008)
5. Government Accountability Office: Key Actions Have Been Taken to Enhance Mass Transit and Passenger Rail Security, but Opportunities Exist to Strengthen Federal Strategy and Programs. Committee on Homeland Security, USA (2009)