1. Epidemiology of helicopter accidents: Trends, rates, and covariates;JS Churchwell;Reliab Eng Syst Safe,2018
2. Maintenance and inspection as risk factors in helicopter accidents: Analysis and recommendations;JH Saleh;PLOS One,2019
3. Herrera I, Håbrekke S, Krakenes T, Hokstad P, Forseth U. Helicopter Safety Study 3. Trondheim, Norway: SINTEF Technology and Society; 2010. Report No. A15753. https://www.sintef.no/globalassets/upload/teknologi_og_samfunn/sikkerhet-og-palitelighet/rapporter/sintef-a15753-helicopter-safety-study-3-_hss-3_-main-report.pdf.
4. Kråkenes T, Evjemo TE, Håbrekke S, Hoem ÅS. Helicopter Safety Study 3b. Trondheim, Norway: SINTEF Technology and Society; 2017. Report No. 2017:00079. https://www.sintef.no/globalassets/sintef-teknologi-og-samfunn/rapporter-sintef-ts/report-hss-3b-en-final-04-07-2015.pdf.
5. A risk influence model applied to North Sea helicopter transport;P Hokstad;Reliab Eng Syst Safe,2001