Keller, Gerta. (2005) 2005. “Biotic Effects of Late Maastrichtian Mantle Plume Volcanism: Implications for Impacts and Mass Extinctions”. Lithos 79 (3-4): 317-41. doi:10.1016/j.lithos.2004.09.005. Reference Link
Pardo, Alfonso, and Gerta Keller. (2008) 2008. “Biotic Effects of Environmental Catastrophes at the End of the Cretaceous and Early Tertiary: Guembelitria and Heterohelix Blooms”. Cretaceous Research 29 (5-6): 1058-73. doi:10.1016/j.cretres.2008.05.031. Reference Link