http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Late cenozoic chronostratigraphy of the Gulf of Mexico
Society of Economic Paleontologists and Mineralogists
"Highly detailed chronostratigraphic chart of the Late Cenozoic of the Gulf of Mexico presents biostratigraphic zonations developed by Shell Offshore Inc. with the Shell Offshore interpretation of commonly used industry zones and related to standard worldwide zonations"--http://www.gcssepm.org/