Mal:Perm-trias-utryddinga grafisk tidslinje
- ↑ 1,0 1,1 Payne, J.L.; Lehrmann, D.J.; Wei, J.; Orchard, M.J.; Schrag, D.P.; Knoll, A.H. (2004). «Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction». Science 305 (5683): 506. PMID 15273391. doi:10.1126/science.1097023.
- ↑ McElwain, J.C.; Punyasena, S.W. (2007). «Mass extinction events og the plant fossil record». Trends in Ecology & Evolution 22 (10): 548–557. doi:10.1016/j.tree.2007.09.003.
- ↑ Retallack GJ Veevers JJ & Morante R (1996). «Global coal gap between Permian–Triassic extinctions and middle Triassic recovery of peat forming plants». GSA Bulletin 108 (2): 195–207. Henta 23. august 2008.