1 . COMMON CUSTOMS TARIFF - SYSTEM OF GENERALIZED PREFERENCES IN FAVOUR OF DEVELOPING COUNTRIES - ORIGIN OF THE GOODS - VERIFICATION - NECESSITY ( REGULATION NO 1371/71 OF THE COMMISSION ) 2 . COMMON CUSTOMS TARIFF - SYSTEM OF GENERALIZED PREFERENCES IN FAVOUR OF DEVELOPING COUNTRIES - ORIGIN OF THE GOODS - VERIFICATION - METHODS - VERIFICATION OF CERTIFICATES OF ORIGIN AFTER IMPORTATION - NEGATIVE OUTCOME - RECOVERY OF DUTIES NOT PAID - LAWFULNESS ( REGULATION NO 1371/71 OF THE COMMISSION , ART . 13 )