Doran, J.A.; van der Graaf, G.C. (1996). Tripod-BETA: Incident investigation and analysis. SPE Health, Safety and Environment in Oil and Gas Exploration and Production Conference, 9.–12. junij 1996. New Orleans, Louisiana: Society of Petroleum Engineers. doi:10.2118/35971-MS.
Gower-Jones, A.D.; van der Graf, G.C. (1998). Experience with Tripod BETA Incident Analysis. SPE International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production, 7.–10. junij 1998. Caracas, Venezuela: Society of Petroleum Engineers. doi:10.2118/46659-MS.
Doran, J.A.; van der Graaf, G.C. (1996). Tripod-BETA: Incident investigation and analysis. SPE Health, Safety and Environment in Oil and Gas Exploration and Production Conference, 9.–12. junij 1996. New Orleans, Louisiana: Society of Petroleum Engineers. doi:10.2118/35971-MS.
Gower-Jones, A.D.; van der Graf, G.C. (1998). Experience with Tripod BETA Incident Analysis. SPE International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production, 7.–10. junij 1998. Caracas, Venezuela: Society of Petroleum Engineers. doi:10.2118/46659-MS.