https://www.nao.org.uk/wp-content/uploads/2018/01/PFI-and-PF2.pdf
https://www.bloomberg.com/graphics/2019-european-capital-markets/
https://link.springer.com/content/pdf/10.1057/s42214-020-00069-3.pdf
https://icsid.worldbank.org/sites/default/files/documents/Code_of_Conduct_V3_Comments_by_State_Commenter.pdf