^Wignall, Paul B., and Anthony Hallam. Mass Extinctions and Their Aftermath. Oxford, Oxford University Press, 1997; pp. 164-5.
^MacLeod, Kenneth G., and Christian Koeberl. Catastrophic Events and Mass Extinctions: Impacts and Beyond. Boulder, CO, Geological Society of America, 2002; pp. 525-9.
^Marti, Joan, and Gerald Ernst. Volcanoes and the Environment. Cambridge, Cambridge University Press, 2005; p. 219.