Regulation (EEC) No 376/73 of the Commission of 31 January 1973 amending, as regards the compensatory amounts provided for in the Act of Accession, Regulations (EEC) Nos 1259/72, 1282/72, 1519/72, 1717/72, 2474/72, 2537/72 and 2561/72 relating to special sales of butter