https://www.occrp.org/en/investigations/calling-london
ftp://ftp.unibocconi.it/pub/RePEc/bcu/papers/iefewp69.pdf
https://pop-umbrella.s3.amazonaws.com/uploads/9dacd52a-6987-4dcb-a90c-4a1146f4a342_Taxing%20Multinationals.pdf
http://ec.europa.eu/transport/sites/transport/files/eu_air_carriers_by_country_holding_an_active_operating_licence.pdf