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Dyfyniad Arddull ChicagoWorld book. World Book Encyclopedia(vol.22.): :research Guide. London: World book international, 1996.
Dyfyniad MLAWorld book. World Book Encyclopedia(vol.22.): :research Guide. World book international, 1996.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.