Cita APA (7a ed.)

Shklovskii, I., & Sagan, C. (1966). Intelligent life in the universe. Holden-Day.

Cita Chicago Style (17a ed.)

Shklovskii, I.S, y Carl Sagan. Intelligent Life in the Universe. San Francisco: Holden-Day, 1966.

Cita MLA (9a ed.)

Shklovskii, I.S, y Carl Sagan. Intelligent Life in the Universe. Holden-Day, 1966.