https://insightcrime.org/wp-content/uploads/2023/05/The-Flow-of-Precursor-Chemicals-for-Synthetic-Drug-Production-in-Mexico-InSight-Crime-March-2023-3.pdf
http://www.bankofengland.co.uk/publications/Documents/fsr/2017/fsrjun17.pdf
http://www.cesifo-group.de/ifoHome/publications/working-papers/CESifoWP/CESifoWPdetails?wp_num=6430&CESifoWP.search=+