1. R. S. Horsfall and L. G. Lawrie,The Dyeing of Textile Fibres, 2nd edn, London, Chapman and Hall (1946), p. 1.
2. C. L. Berthollet, Elements de l’Art de la Teinture, Paris (1791). Translated into English by W. Hamilton; London, J. Johnston (1791), 2 vols, p. ii.