Changes to 63/27/Euratom: Council Decision of 18 June 1963 on the establishment of the 'Kernkraftwerk RWE-Bayernwerk GmbH' Joint Undertaking
EU Decision 1963/27
Made by 66/19/Euratom: Council Decision of 14 June 1966 approving a third amendment to the Statutes of the 'Kernkraftwerk Rheinisch-Westfälisches Elektrizitätswerk-Bayernwerk GmbH' Joint Undertaking
From legislation.gov.uk's record of changes, the official one: see it there.