https://www.brookings.edu/articles/kazakhstan-advance-market-reforms-first-pour-concrete-later/
http://www.ips-journal.eu/regions/global/article/show/davos-2018-call-the-doctor-2544/
https://blogs.lse.ac.uk/europpblog/2023/06/19/is-differentiated-cooperation-the-way-forward-for-eu-foreign-policy/