APA (7th ed.) Zitazioa
Black Book - Valero Energy Corporation (1982). Bernstein Institutional Services LLC.
Chicago Style (17th ed.) Zitazioa
Black Book - Valero Energy Corporation (1982). Bernstein Institutional Services LLC.
MLA (9th ed.) Zitazioa
Black Book - Valero Energy Corporation (1982). Bernstein Institutional Services LLC.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.