APA (7th ed.) Citation

Ellis, P. B. (1990). The Celtic empire: The first millennium of Celtic history c. 1000 BC - 51 AD (1. publ.). Constable.

Chicago Style (17th ed.) Citation

Ellis, Peter Berresford. The Celtic Empire: The First Millennium of Celtic History C. 1000 BC - 51 AD. 1. publ. London: Constable, 1990.

MLA (9th ed.) Citation

Ellis, Peter Berresford. The Celtic Empire: The First Millennium of Celtic History C. 1000 BC - 51 AD. 1. publ. Constable, 1990.

Warning: These citations may not always be 100% accurate.