Reference for a preliminary ruling by the First Chamber of the Efetio Athinon (Court of Appeal, Athens), by a judgment of that court of 6 June 1996 in the case of Alexandros Kefalas and Others v. Greek State and Organismos Ikonomikis Anasinkrotisis Epikhirseon AE and Others - Interveners: Athinaiki Khartopiia AE and Others (Case C-367/96)