1. Wikipedia. List of rail accidents (2000–2009) — Wikipedia, the free encyclopedia, 2010.
2. Automated consistency checking of requirements specifications;Heitmeyer;ACM Trans. Softw. Eng. Methodol.,1996
3. GAO. Mission critical systems: defense attempting to address major software challenges. Technical report, GAO/IMTEC-93-13, U.S. General Accounting Office, Washington, D.C., 1992.
4. European Committee Electro Technical Standardization. Railway applications communications’, ’signalling and processing systems software for railway control & protection systems, 2001.
5. T.A. Alspaugh, S.R. Faulk, K.H. Britton, R.A. Parker, D.L. Parnas, J.E. Shore, Software requirements for the a-7e aircraft. Technical report, NRL-9194, Naval Research Laboratory, 1992.