Terms sourced from: http://iupac.org/publications/pac/69/5/1007/

"Reference value standards and primary standards for pH measurements in D2O and aqueousorganic solvent mixtures: New accessions and assessments (Technical Report)", Mussini, P.R.;Mussini, T.;Rondinini, S., Pure And Applied Chemistry 1997, 69(5), 1007

pH