APA (7th ed.) Citation

Duckworth, H. E. (1963). Little men in the unseen world: A guide to atomic physics. Macmillan.

Chicago Style (17th ed.) Citation

Duckworth, Henry E. Little Men in the Unseen World: A Guide to Atomic Physics. London: Macmillan, 1963.

MLA (9th ed.) Citation

Duckworth, Henry E. Little Men in the Unseen World: A Guide to Atomic Physics. Macmillan, 1963.