The Activity Atlas
Contact
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No contact email is published on this site, and no author names are published. That is an honest statement, not an omission to be filled with an invented address.
For a code itself, use the UN Statistics Division structure and the national statistical institute or business register that holds the record. For a correction to a guide, note the guide title and the statement in question, and raise it through the channel that published the correction policy on this site when one is added.