1. “Porphyrins and Metalloporphyrins,” K.M. Smith, Ed., Elsevier, Amsterdam, 1975.
2. “The Porphyrins,” D. Dolphin, Ed., Academic Press, New York, N.Y., in press.
3. F. R. Hopf and D. G. Whitten, in ref. 1 “. p. 667.
4. D. Mauzerall and F. T. Hong, in ref. 1 “, p. 701.
5. For a review on porphyrin stereochemistry, see W. R. Scheidt,Acct. Chem. Res., in press.