Burgess et al. (2014)
Also: Burgess et al. 2014
High-precision timeline for Earths most severe extinction
Burgess, S. D., Bowring, S., & Shen, S. Z. (2014). High-precision timeline for Earths most severe extinction. Proceedings of the National Academy of Science 111(9), 3316-3321. Link to PDF
doi: 10.1073/pnas.131769211
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.