World book. (1996). World book encyclopedia(vol.22.): :research guide. World book international.
Chicago Style aipamenaWorld book. World Book Encyclopedia(vol.22.): :research Guide. London: World book international, 1996.
MLA aipamenaWorld book. World Book Encyclopedia(vol.22.): :research Guide. World book international, 1996.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.