(1993). Annual report 1998. Vienna: OPEC.
Trích dẫn kiểu ChicagoAnnual Report 1998. Vienna: OPEC, 1993.
Deismireacht MLAAnnual Report 1998. Vienna: OPEC, 1993.
Rabhadh: D'fhéadfadh nach mbeadh na deismireachtaí seo 100% cruinn i gcónaí.
Deismireacht APA