World Book. (1996). World Book Encyclopedia - P(vol.15). World Book International.
Chicago Style aipamenaWorld Book. World Book Encyclopedia - P(vol.15). London: World Book International, 1996.
MLA aipamenaWorld Book. World Book Encyclopedia - P(vol.15). World Book International, 1996.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.