Cita APA (7a ed.)
Hayes, D. (1977). Rays of hope: The transition to a post-petroleum world. Worldwatch Institute.
Cita estilo Chicago (17a ed.)
Hayes, Denis. Rays of Hope: The Transition to a Post-petroleum World. Nueva York, EUA: Worldwatch Institute, 1977.
Cita MLA (9a ed.)
Hayes, Denis. Rays of Hope: The Transition to a Post-petroleum World. Worldwatch Institute, 1977.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.