++++ COMMUNITY LAW - PRINCIPLES - EQUAL TREATMENT - DISCRIMINATION ON GROUNDS OF NATIONALITY - PRODUCTION - NATIONAL LEGISLATION ON THE PRICE OF BOOKS - DIFFERENT TREATMENT OF RE-IMPORTED BOOKS - PERMISSIBILITY ( EEC TREATY, ART . 7 ) FREE MOVEMENT OF GOODS - QUANTITATIVE RESTRICTIONS - MEASURES HAVING EQUIVALENT EFFECT - NATIONAL LEGISLATION ON THE PRICE OF BOOKS - DIFFERENT TREATMENT OF RE-IMPORTED BOOKS - PERMISSIBILITY ( EEC TREATY, ART . 30 )