https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.37.4.115
https://insightcrime.org/wp-content/uploads/2023/05/El-flujo-de-precursores-quimicos-para-la-produccion-de-drogas-sinteticas-en-Mexico-InSight-Crime-May-2023.pdf
https://www.publications.parliament.uk/pa/cm201617/cmselect/cmscotaf/82/82.pdf
https://www.esri.ie/system/files/publications/RS152.pdf