Gon, G (2020). CLEAN study dataset. [Data Collection]. London School of Hygiene & Tropical Medicine, London, United Kingdom. https://doi.org/10.17037/DATA.00001937.

Roberts, J, Allen, P, Croxson, B, Taylor, L, Crawshaw, S and Archibald, K (2000). Risks, Contracts and Infectious Disease in the UK NHS Managed Market, 1997-1999. [Data Collection]. UK Data Service, Essex, United Kingdom. https://doi.org/10.5255/UKDA-SN-4151-1