Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J.-X. (January 2020). "International Chronostratigraphic Chart"(PDF). International Commission on Stratigraphy. Retrieved 23 February 2020.
Cohen, K. M.; Finney, S. C.; Gibbard, P. L.; Fan, J.-X. (January 2020). "International Chronostratigraphic Chart"(PDF). International Commission on Stratigraphy. Retrieved 23 February 2020.