Cita APA (7th ed.)
Hayes, D. (1977). Rays of hope: The transition to a post-petroleum world. Norton.
Cita Chicago (17th ed.)
Hayes, Denis. Rays of Hope: The Transition to a Post-petroleum World. New York: Norton, 1977.
Cita MLA (9th ed.)
Hayes, Denis. Rays of Hope: The Transition to a Post-petroleum World. Norton, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.