ScienceDirect (Online service) & Gradstein, F. M. (2012). The Geologic time scale 2012. Elsevier.
Chicago Style (17th ed.) CitationScienceDirect (Online service) and F. M. Gradstein. The Geologic Time Scale 2012. [Oxford, U.K.]: Elsevier, 2012.
MLA (9th ed.) CitationScienceDirect (Online service) and F. M. Gradstein. The Geologic Time Scale 2012. Elsevier, 2012.
Warning: These citations may not always be 100% accurate.