1. General System Theory;von Bertalanffy L.;General Systems,1956
2. Calvo-Amodio J. andRousseauD.2019. ‘The Human Activity System: Emergence from Purpose Boundaries Relationships and Context.’Proceedings of the 17th Annual Conference on Systems Engineering Research Washington DC 3–4April.
3. CED. n.d. ‘Principle (Definition)’. Accessed 29 September 2017.http://dictionary.cambridge.org/dictionary/english/principle.
4. P. Collopy B. Mesmer 53rd AIAA Aerospace Sciences Meeting 2014 AIAA Kissimmee FL 1 4
5. Defoe J.1993. ‘An Identification of Pragmatic Principles-Final Report.’ National Council on Systems Engineering.