APA (7th ed.) Citation

John Wyndham. (1951). The Day of the Triffids. Penguin Books Ltd.

Chicago Style (17th ed.) Citation

John Wyndham. The Day of the Triffids. Britain: Penguin Books Ltd, 1951.

MLA (9th ed.) Citation

John Wyndham. The Day of the Triffids. Penguin Books Ltd, 1951.

Warning: These citations may not always be 100% accurate.