APA (7th ed.) Citation

Ashworth, W. (1977). Hells Canyon, the deepest gorge on earth. Hawthorn Books.

Chicago Style (17th ed.) Citation

Ashworth, William. Hells Canyon, the Deepest Gorge on Earth. New York: Hawthorn Books, 1977.

MLA (9th ed.) Citation

Ashworth, William. Hells Canyon, the Deepest Gorge on Earth. Hawthorn Books, 1977.