APA

Silverberg R., . (1983). Across a billion years. New York: Dial Press.

Chicago

Silverberg Robert, . 1983. Across a billion years. New York: Dial Press.

Harvard

Silverberg R., . (1983). Across a billion years. New York: Dial Press.

MLA

Silverberg Robert, . Across a billion years. New York: Dial Press. 1983.