APA (7th ed.) Citation

Ludlum, R., & Menini, M. A. El protocolo Sigma.

Chicago Style (17th ed.) Citation

Ludlum, Robert, and Maria Antonia Menini. El Protocolo Sigma. Barcelona.

MLA (9th ed.) Citation

Ludlum, Robert, and Maria Antonia Menini. El Protocolo Sigma.

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