Crutzen, P. Atmospheric Chemistry, Max Planck Institute for Chemistry, Max Planck Society;
Rockström, J., Steffen, W., Noone, K., Persson, A., Chapin, F. S., Lambin, E. F., et al. (2009). Planetary Boundaries: Exploring the Safe Operating Space for Humanity. Ecology and Society, 14(2): art 32.