1. McGlashan ML (1971) Physico-Chemical Quantities and Units. Royal Institute of Chemistry, London
2. Lang PF, Smith BC (1986) Educ Chem 23:50
3. Mingos DMP (1995) Essentials of Inorganic Chemistry 1. Oxford University Press, Oxford
4. Moore CE (1949) Atomic energy levels, vol 1. US Department of Commerce, Washington DC
5. Moore CE (1952) Atomic energy levels, vol 2. US Department of Commerce, Washington DC