1. Cybersecurity & Infrastructure Security Agency (CISA). Shields up | CISA. www.cisa.gov, www.cisa.gov/shields-up
2. Shertz K (2018) The five Ds: securing the nation’s aviation infrastructure. 23 Mar 2018
3. Gilman E, Barth D (2017) Zero trust networks: building secure systems in untrusted networks. O’reilly Media, Sebastopol, CA
4. Marsh S (1994) Formalising trust as a computational concept
5. Poe M (2021) Building a zero trust security plan for your company—BeyondID, Inc. BeyondID, 29 Mar 2021. www.beyondid.com/resources/zero-trust-security-plan. Accessed 25 Feb 2022