APA (7th ed.) Citation

Silverberg, R. (1977). Across a billion years. Gollancz.

Chicago Style (17th ed.) Citation

Silverberg, Robert. Across a Billion Years. London: Gollancz, 1977.

MLA (8th ed.) Citation

Silverberg, Robert. Across a Billion Years. Gollancz, 1977.

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