COUNCIL REGULATION (EC) No 3667/93 of 20 December 1993 supplementing Regulation (EEC) No 3917/92 extending into 1993 the application of Regulations (ECC) No 3831/90, (EEC) No 3832/90, (EEC) No 3833/90, (EEC) No 3834/90, (EEC) No 3835/90 and (EEC) No 3900/91 applying generalized tariff preferences for 1991 in respect of certain products originating in developing countries and adding to the list of beneficiaries of such preferences