COMMON CUSTOMS TARIFF - IMPORTATION FREE OF CUSTOMS DUTIES - SCIENTIFIC MATERIALS - ' ' COMPONENTS , SPARE PARTS OR ACCESSORIES ' ' OF A COMPLEX INSTALLATION FOR SCIENTIFIC RESEARCH - CLASSIFICATION AS SCIENTIFIC INSTRUMENTS OR APPARATUS - PERMISSIBILITY - GRANT OF DUTY-FREE ADMISSION - CONDITIONS ( REGULATION ( EEC ) NO 1798/75 OF THE COUNCIL , ART . 3 ( 1 ) AND ( 2 ))