Cita APA (7a ed.)

George, R. P., & Tollefsen, C. (2008). Embryo: A defense of human life. Doubleday.

Cita Chicago Style (17a ed.)

George, Robert P., y Christopher Tollefsen. Embryo: A Defense of Human Life. New York [etc.]: Doubleday, 2008.

Cita MLA (9a ed.)

George, Robert P., y Christopher Tollefsen. Embryo: A Defense of Human Life. Doubleday, 2008.