1. McCance RA, Widdowson EM (1956) Mediaeval and early modern England (1200–1700). In: McCance RA, Widdowson EM (eds), Breads, white and brown; their place in thought and social history. Pitnam Med Publ Co, London: 10–27.
2. Heyder M (1979) Amsterdam — korenschuur van Europa. Amsterdam: Stadsdrukkerij van Amsterdam, 104 pp.
3. Jacob HE (1956) Sechstausend Jahre Brot. 2nd ed. Rohwolt Verlag, Hamburg: 335–378.
4. Maynard Smith J (1958) The theory of evolution. Penguin Books, Middlesex: 226–227.
5. Peterson RF (1965a) Species. In: Peterson RF (ed), Wheat: botany, cultivation and utilization. Leonard Hill Books, London and Intersc Publ, New York: 1–16.