Changes made by Council Directive of 29 March 1977 on the approximation of the laws of the Member States relating to the driver-perceived noise level of wheeled agricultural or forestry tractors (77/311/EEC)
EU Directive 1977/311
No changes made by Council Directive of 29 March 1977 on the approximation of the laws of the Member States relating to the driver-perceived noise level of wheeled agricultural or forestry tractors (77/311/EEC) are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.