. . . "\"Relative Atomic Mass \" is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12 (known as the unified atomic mass unit)" . . . . . . "A_r" . "http://en.wikipedia.org/wiki/Relative_atomic_mass"^^ . . . "http://www.iso.org/iso/catalogue_detail?csnumber=31894"^^ . . "Relative Atomic Mass"@en . . . . .