http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
pt. A. Systems with one element -- pt. B. Systems with two elements -- pt. C. Systems with three or four elements.
Subtitle: The complete GAPHYOR literature database of physico-chemical properties and processes involving neutral and ionized atoms, and simple molecules in the gas phase for the years 1970-1986.