Council Regulation (EEC) No 3138/76 of 21 December 1976 amending Regulations (EEC) No 2682/72, (EEC) No 2727/75, (EEC) No 765/68 and (EEC) No 3330/74 as regards the description of certain chemicals falling within subheading 29.16 A ex VIII of the Common Customs Tariff