Cita APA (7th ed.)
Richards, R. J. (2008). The tragic sense of life: Ernst Haeckel and the struggle over evolutionary thought. University of Chicago Press.
Cita Chicago (17th ed.)
Richards, Robert J. The Tragic Sense of Life: Ernst Haeckel and the Struggle over Evolutionary Thought. Chicago: University of Chicago Press, 2008.
Cita MLA (9th ed.)
Richards, Robert J. The Tragic Sense of Life: Ernst Haeckel and the Struggle over Evolutionary Thought. University of Chicago Press, 2008.
Atenció: Aquestes cites poden no estar 100% correctes.