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Dyfyniad Arddull ChicagoReid, Walter V., and Kenton R. Miller. Keeping Options Alive: The Scientific Basis for Conserving Biodiversity. Washington, D.C: World Resources Institute, 1989.
Dyfyniad MLAReid, Walter V., and Kenton R. Miller. Keeping Options Alive: The Scientific Basis for Conserving Biodiversity. World Resources Institute, 1989.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.