APA (7th ed.) Citation

LUDLUM. (2001). The sigma protocol. St. Martins Paperbacks.

Chicago Style (17th ed.) Citation

LUDLUM. The Sigma Protocol. New York: St. Martins Paperbacks, 2001.

MLA (9th ed.) Citation

LUDLUM. The Sigma Protocol. St. Martins Paperbacks, 2001.

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