Mace, G. M., Akcakaya, H. R., Collar, N. J., Gaston, K. J., Hilton Taylor, C., Leader Williams, N., . . . Stuart, S. N. Quantification of extinction risk: IUCN´s system for classifying threatened species.

Mace, Georgina M., H. Resit Akcakaya, Nigel J. Collar, Kevin J. Gaston, Craig Hilton Taylor, Nigel Leader Williams, E. J. Milner Gulland, and Simon N. Stuart. Quantification of Extinction Risk: IUCN´s System for Classifying Threatened Species.

Mace, Georgina M., et al. Quantification of Extinction Risk: IUCN´s System for Classifying Threatened Species.