1. ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod) Functional Safety: Safety Instrumented Systems for the Process Industry Sector-Part 1: Framework, Definitions, System, Hardware and Software Requirements
2. ANSI/ISA-84.00.01-2004 Part 2 (IEC 61511-2 Mod) Functional Safety: Safety Instrumented Systems for the Process Industry Sector-Part 2: Guidelines for the Application of ANSI/ISA-84.00.01-2004 Part 1 (IEC 61511-1 Mod)
3. ANSI/ISA-84.00.01-2004 Part 3 (IEC 61511-3 Mod) Functional Safety: Safety Instrumented Systems for the Process Industry Sector-Part 3: Guidance for the Determination of the Required Safety Integrity Levels-Informative
4. ALARP Suite of Guidance, United Kingdom Health and Safety Executive http://www.hse.gov.uk/risk/theory/alarp.htm