国際層序委員会
↑ Riccardi, A.C. (2009年6月30日). “Ratification of the definition of the base of Quaternary System/Period (and top of the Neogene System/Period), and redefinition of the base of the Pleistocene Series/Epoch (and top of the Pliocene Series/Epoch)”. International Union of Geological Sciences. 2011年12月30日閲覧。
↑ Kerr, Richard A. (25 January 2008). “A Time War Over the Period We Live In”. Science 319 (5862): 402–403. doi:10.1126/science.319.5862.402. PMID 18218875.
↑ Gibbard, Philip L.; & al. (2009). “Formal ratification of the Quaternary System/Period and the Pleistocene Series/Epoch with a base at 2.58 Ma”. Journal of Quaternary Science 25 (2): 96–102. doi:10.1002/jqs.1338.