Παραπομπή APA

Zeilik, M. (1979). Astronomy: The evolving universe (2.).

Παραπομπή Chicago Style

Zeilik, Michael. Astronomy: The Evolving Universe. 2. Harper & Brother Publishers, New York, 1979.

Παραπομπή MLA

Zeilik, Michael. Astronomy: The Evolving Universe. 2. 1979.