Pan, I. L. (1998). Oil import bill surges 22% to $3B in 1997. Manila Times.
Chicago Style aipamenaPan, Isabel L. "Oil Import Bill Surges 22% to $3B in 1997." Manila Times 1998.
MLA aipamenaPan, Isabel L. "Oil Import Bill Surges 22% to $3B in 1997." Manila Times, 1998.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.