Changes made by Council Directive of 17 May 1977 on the approximation of the laws of the Member States relating to motor-vehicle towing-devices (77/389/EEC)
EU Directive 1977/389
No changes made by Council Directive of 17 May 1977 on the approximation of the laws of the Member States relating to motor-vehicle towing-devices (77/389/EEC) are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.