Changes to 91/237/EEC: Commission Decision of 25 April 1991 concerning further protection measures relating to a new pig disease
EU Decision 1991/237
Made by 92/104/EEC: Commission Decision of 27 January 1992 amending, for the second time, Decision 91/237/EEC concerning further protection measures relating to a new pig disease
From legislation.gov.uk's record of changes, the official one: see it there.