1. Democritos [of Abdera], quoted in Mackay AL (1991) A dictionary of scientific quotations. Adam Hilger, Bristol
2. Kepler J (1611) Strena seu de nive sexangula. Godefridum Tampach, Francofurti ad Moenum (English translation 1966) The six-cornered snowflake. Oxford, Clarendon Press
3. Dalton J (1805) Memoirs and proceedings of the manchester literary and philosophical society, vol. 6, Manchester, p 271 (Alembic Club Reprints 1961, Edinburgh, no 2, p 15)
4. Einstein A (1954) Ideas and opinions. Crown Publishers, New York, p 266
5. Hargittai I (2000) Frank H Westheimer. In: Hargittai M (ed) Candid science: conversations with famous chemists. Imperial College Press, London, pp 38–53 (the actual quotation is on pp 41–42)