"Notable Signers". Humanism and Its Aspirations. American Humanist Association. Diarsipkan dari versi asli tanggal 2012-10-05. Diakses tanggal October 1, 2012.
Steffen, W.; Grinevald, J.; Crutzen, P.; McNeill, J. (2011). "The Anthropocene: conceptual and historical perspectives". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1938): 842–867. Bibcode:2011RSPTA.369..842S. doi:10.1098/rsta.2010.0327. ISSN1364-503X. PMID21282150.
Steffen, W.; Grinevald, J.; Crutzen, P.; McNeill, J. (2011). "The Anthropocene: conceptual and historical perspectives". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1938): 842–867. Bibcode:2011RSPTA.369..842S. doi:10.1098/rsta.2010.0327. ISSN1364-503X. PMID21282150.
Steffen, W.; Grinevald, J.; Crutzen, P.; McNeill, J. (2011). "The Anthropocene: conceptual and historical perspectives". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1938): 842–867. Bibcode:2011RSPTA.369..842S. doi:10.1098/rsta.2010.0327. ISSN1364-503X. PMID21282150.
"Notable Signers". Humanism and Its Aspirations. American Humanist Association. Diarsipkan dari versi asli tanggal 2012-10-05. Diakses tanggal October 1, 2012.
"P.J. Crutzen". Royal Netherlands Academy of Arts and Sciences. Diarsipkan dari versi asli tanggal 21 July 2015.
worldcat.org
Steffen, W.; Grinevald, J.; Crutzen, P.; McNeill, J. (2011). "The Anthropocene: conceptual and historical perspectives". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1938): 842–867. Bibcode:2011RSPTA.369..842S. doi:10.1098/rsta.2010.0327. ISSN1364-503X. PMID21282150.