APA (7th ed.) Citation

Matthews, J., Stewart, R. J., & Field, J. (1993). Celtic warrior chiefs. Firebird Books.

Chicago Style (17th ed.) Citation

Matthews, John, R. J. Stewart, and James Field. Celtic Warrior Chiefs. Poole, Dorset: Firebird Books, 1993.

MLA (9th ed.) Citation

Matthews, John, et al. Celtic Warrior Chiefs. Firebird Books, 1993.