http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Q-mode factor analysis of geochemical and petrologic data matrices with constant row-sums
Extension of method of Q-mode factor (vector) analysis to increase its usefulness in geochemical and petrologic investigations.
Geological Survey professional paper ; 574-G
Statistical studies in field geochemistry