APA (7th ed.) Zitazioa
Gas Utilities Industry Profile: Eastern Europe. Marketline.
Chicago Style (17th ed.) Zitazioa
Gas Utilities Industry Profile: Eastern Europe. Marketline.
MLA (9th ed.) Zitazioa
Gas Utilities Industry Profile: Eastern Europe. Marketline.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.