APA (7th ed.) Citation

Darwin, C. R. (1877). The different forms of flowers on plants of the same species. John Murray.

Chicago Style (17th ed.) Citation

Darwin, Charles Robert. The Different Forms of Flowers on Plants of the Same Species. London: John Murray, 1877.

MLA (9th ed.) Citation

Darwin, Charles Robert. The Different Forms of Flowers on Plants of the Same Species. John Murray, 1877.