7IEC. IEC 61508 Functional Safety of Electrical/Electronic/ Programmable Electronic Safety-related System, Part 1 - 7 [S]. 2. 0^th. Genvea: International Electrotechnical Commission, 2010.
8IEC. IEC 61511 Functional Safety-Safety Instrumented Systems for the Process Industry Section Part 1 - 3 [S]. Genvea.. International Electrotechnical Commission, 2003.