APA (7th ed.) Citation

Greene, B., & Greene, G. (1990). Too late to turn back: Barbara and Graham Greene in Liberia. Penguin Books.

Chicago Style (17th ed.) Citation

Greene, Barbara, and Graham Greene. Too Late to Turn Back: Barbara and Graham Greene in Liberia. London: Penguin Books, 1990.

MLA (9th ed.) Citation

Greene, Barbara, and Graham Greene. Too Late to Turn Back: Barbara and Graham Greene in Liberia. Penguin Books, 1990.