APA (7th ed.) Citation

Duncan, J. C. (1942). Essentials of astronomy. [publisher not identified].

Chicago Style (17th ed.) Citation

Duncan, John Charles. Essentials of Astronomy. New York, London: [publisher not identified], 1942.

MLA (9th ed.) Citation

Duncan, John Charles. Essentials of Astronomy. [publisher not identified], 1942.

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