Cohen, Kim Mikkel, David A. T. Harper, Philip Leonard Gibbard, and Junxuan Fan. The ICS International Chronostratigraphic Chart. International Commission on Stratigraphy. [15 July 2018]. (原始内容存档于2017-01-13).
International Commission on Stratigraphy. GSSP Table - All Periods. GSSPs. [15 July 2018]. (原始内容存档于2012-11-15).
Cohen, Kim Mikkel, David A. T. Harper, Philip Leonard Gibbard, and Junxuan Fan. The ICS International Chronostratigraphic Chart. International Commission on Stratigraphy. [15 July 2018]. (原始内容存档于2017-01-13).