1. V.H. Booth, Biochem. J. 87, 238 (1963).
2. L. Zechmeister, quoted by W. Karrer, Konstitution und Vorkommen der organischen Pflanzenstoffe (Birkhäuser, Basle 1958), p. 716.
3. P. Karrer and E. Jucker, Carotinoide (Birkhäuser, Basle 1948); English translation by E. A. Braude (Elsevier, Amsterdam 1950).
4. T. W. Goodwin, The Comparative Biochemistry of the Carotenoids (Chapman and Hall, London 1952). Second edition in preparation.
5. T. W. Goodwin, in Chemistry and Biochemistry of Plant Pigments, ed. by T. W. Goodwin, (Academic Press, London 1965), p. 127.