Changes made by 83/470/EEC: Commission Decision of 7 September 1983 concerning the establishments in the United Mexican States from which Member States may authorize the importation of fresh meat
EU Decision 1983/470
No changes made by 83/470/EEC: Commission Decision of 7 September 1983 concerning the establishments in the United Mexican States from which Member States may authorize the importation of fresh meat are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.