1. Burke, J.G. (1966) Origins of the science of crystals, University California Press, Berkeley and Los Angeles.
2. International Union of Crystallography, International Tables for X-ray Crystallography (1969) Kynoch Press, Birmingham, England
3. Phillips, F.C. (1963 and more recent prints) An introduction to Crystallography, Longman, London.
4. Hartman, P. and Perdok, W.G. (1955) Acta Cryst. 8, 49.
5. Hartman, P. and Perdok, W.G. (1955) Acta Cryst. 8, 521.