1. Ching Pen-po, Yen-wu ko-ming shih (A history of the revolution in the salt administration) (Ching-yen tsung-hui yen-cheng tsa-che she, Nanking, 1929).
2. Marco Polo, The Travels of Marco Polo (Penguin, Harmondsworth, 1958) p. 209.
3. Ibid., p. 188.
4. Donald F. Lach, Asia in the Making of Europe, Volume I, The Century of Discovery, Book One (University of Chicago Press, Chicago and London, 1965) p. 144.
5. See also M. A. P. Meilink-Roelofsz, Asian Trade and European Influence (Martinus Nijhoff, The Hague, 1962) p. 224 for an estimate of pepper sales in Europe in 1621.