1. H.H. Strain, Leaf Xanthophylls (Carnegie Institute Publication No. 490, Washington 1938).
2. P. Karrer and E. Jucker, Carotenoids (Elsevier, Amsterdam 1950).
3. T. W. Goodwin, in Modern Methods of Plant Analysis, ed. by K. Peach and M. V. Tracey (Springer, Heidelberg 1955), p. 273.
4. B. H. Davies, in Chemistry and Biochemistry of Plant Pigments, ed. by T. W. Goodwin (Academic Press, London 1965), p. 489.
5. S. Liaaen-Jensen and A. Jensen, Progr. Chem. Fats Other Lipids 8, 129 (1965).