https://wits.worldbank.org/product_concordance.html

https://unstats.un.org/unsd/classifications/Econ

https://ec.europa.eu/eurostat/ramon/relations/index.cfm?TargetUrl=LST_REL_DLD&StrNomRelCode=ISIC%20REV.%203%20-%20SITC%20REV.%203&StrLanguageCode=EN&StrOrder=1&CboSourceNomElt=&CboTargetNomElt=&IntCurrentPage=1
https://ec.europa.eu/eurostat/ramon/relations/index.cfm?TargetUrl=LST_REL

https://wooxiaokang.weebly.com/blog/concordence-between-cicisichs-and-sitc