Couto 1989, p. 315. Couto, Richard A. (June 1989). "Economics, Experts, and Risk: Lessons from the Catastrophe at Aberfan". Political Psychology. 10 (2): 309–324. doi:10.2307/3791650. JSTOR3791650.
Davey 1976, pp. 178–79. Davey, Christopher J. (1976). "The Structural Failure of the Meidum Pyramid". The Journal of Egyptian Archaeology. 62: 178–179. doi:10.2307/3856360. JSTOR3856360.
geolsoc.org.uk
Nield 2016. Nield, Ted (October 2016). "Tipping point". The Geological Society of London. Archived from the original on 12 August 2017. Retrieved 6 August 2017.
Couto 1989, p. 315. Couto, Richard A. (June 1989). "Economics, Experts, and Risk: Lessons from the Catastrophe at Aberfan". Political Psychology. 10 (2): 309–324. doi:10.2307/3791650. JSTOR3791650.
Davey 1976, pp. 178–79. Davey, Christopher J. (1976). "The Structural Failure of the Meidum Pyramid". The Journal of Egyptian Archaeology. 62: 178–179. doi:10.2307/3856360. JSTOR3856360.
Nield 2016. Nield, Ted (October 2016). "Tipping point". The Geological Society of London. Archived from the original on 12 August 2017. Retrieved 6 August 2017.