Cita APA (7a ed.)
Gray, W. R. Powers of Nature. National Geographic Society, Special Publications Division.
Cita estilo Chicago (17a ed.)
Gray, William R. Powers of Nature. Washington, EUA: National Geographic Society, Special Publications Division.
Cita MLA (9a ed.)
Gray, William R. Powers of Nature. National Geographic Society, Special Publications Division.
Precaución: Estas citas no son 100% exactas.