1. P. F. Gordon and P. Gregory, in; Organic Chemistry in Color,Spriner-Verlag, Berlin (1983).
2. P. F. Gordon and P. Gregory, in; Organic Chemistry in Color,Spriner-Verlag, Berlin (1983) p. 4.
3. P. F. Gordon and P. Gregory, in; Organic Chemistry in Color,Spriner-Verlag, Berlin (1983) p. 3.
4. P. F. Gordon and P. Gregory, in; Organic Chemistry in Color,Spriner-Verlag, Berlin (1983) p. 6.
5. P. F. Gordon and P. Gregory, in; Organic Chemistry in Color,Spriner-Verlag, Berlin (1983) pp. 8–21.