8Defense Industry Daily. F22 squadron shot down by the International Date Line [ EB/OL]. http://www, defenseindustrydaily. com/f22-squadron shot down by-thc-international-date-line- 03087/,2007-3-1.
9USAF. MIL-STD-1574A- 1979 System safety program for space and missile system[S]. Arlington: Department of Defence, 1979.
10Leveson N G. Software safety: why, what, and how[J]. Computing Surveys, 1986,18(2) : 125-163.