Não informado. (1968). Annual Bulletin of General Energy Statistics for Europe. United Nations, Economic Commission for Europe.
শিকাগো স্টাইল (17 তম সংস্করণ) উদ্ধৃতিNão informado. Annual Bulletin of General Energy Statistics for Europe. New York: United Nations, Economic Commission for Europe, 1968.
M.L.A (8 ম সংস্করণ) উদ্ধৃতিNão informado. Annual Bulletin of General Energy Statistics for Europe. United Nations, Economic Commission for Europe, 1968.
সতর্কবাণী: সাইটেশন সবসময় 100% নির্ভুল হতে পারে না.