Regulation (EEC) no 1191/69 of the Council of 26 June 1969 on action by member states concerning the obligations inherent in the concept of a public service in transport by rail, road and inland waterway - European Commission. (Υπηρεσία Επισήμων Εκδόσεων των ΕυρωπαΪκών κοινοτήτων, 1996)