Ehrlich, Paul R. Ehrlich & Anne H. (1990). The population explosion. London: Hutchinson. pp. 39–40. ISBN0091745519. Consultado el 20 de julio de 2014. «When is an area overpopulated? When its population can not be maintained without rapidly depleting non-renewable resources [39] (or converting renewable resources into non-renewable ones) and without decreasing the capacity of the environment to support the population. In short, if the long-term carrying capacity of an area is clearly being degraded by its current human occupants, that area is overpopulated.»
