1. N. B. McKeown, Phthalocyanine Materials: Synthesis, Structure and Function (Cambridge University Press, London, 1998) p. 14.
2. C. C. Leznoff, Phthalocyanines: Properties and Applications 1, eds. C. C. Leznoff and A. B. P. Lever (VCH Publishers, Cambridge, 1989) pp. 1–54.