1. NPR 8000.4B, Agency risk management procedural requirements, section 3.4.2 i (1), pg. 21.
2. NASA/SP-2011-3421, Probabilistic risk assessment procedures guide for NASA managers and practitioners.
3. E. Honour, 2013, Systems engineering return on investment, PhD Thesis, University of South Australia. 12 p.
4. S. Darpel & S. Beckman, Early engagement of safety & mission assurance expertise using systems engineering tools: a risk-based approach to early identification of safety and assurance requirements, Proceedings of the Ninth IAASS Conference.