6Mathis Wackemagel & William Rees. Our Ecological footprint: Reducing Human Impact on the Earth[M]. New Society Publishers, Gabfiola Island,BC,30 - 100.
7Mathis Wackernagel. World Ecological Foolprint Report. www. reprogress.com.
8Mathis Wackernagel , Niels B. Schulz, Diarma Deumling. Tracking the Ecological Overshoot of the Human Economy[J]. PNAS,2002.99.
