1. C. Nwagboso, P. Georgakis and D. Dyke: Computers in Industry, Vol. 54 (2004), pp.291-306.
2. J.G. Wang, W.Y. Wang, F. Tian and J.B. Wei: Journal of Traffic and Transportation Engineering, (2005), No. 2, pp.106-109. (In Chinese).
3. G.J. Myers: Software Reliability Principles and Practices (Wiley Interscience, U.S.A. 1976).
4. M. Xie: Applied Stochastic Models and Data Analysis, Vol. 6 (1990), No. 4, pp.207-213.