Zirnstein, G. (1982). Charles Darwin. Teubner.
Cita Chicago (17th ed.)Zirnstein, Gottfried. Charles Darwin. Leipzig: Teubner, 1982.
Cita MLA (8th ed.)Zirnstein, Gottfried. Charles Darwin. Teubner, 1982.
Atenció: Aquestes cites poden no estar 100% correctes.