
https://www.cesifo-group.de/DocDL/ifoDD_18-01_29-31_Achten.pdf

https://www.openmarketsinstitute.org/publications/sling-de-economizing-antitrust-law-starts-with-market-definition

https://documents1.worldbank.org/curated/en/099152301082423951/pdf/IDU10e3b5c3c1eb9214f981ad6116416052537cd.pdf