1. 1) (a) A. O. Patil, A. J. Heeger, F. Wudl, Chem. Rev., 88, 183 (1988)
2. (b) J. Roncali, Chem. Rev., 97, 173 (1997)
3. (c) W. Friedrichsen, Adv. Heterocyl. Chem., 26, 135 (1980)
4. (d) W. Friedrichsen, Adv. Heterocyl. Chem., 73, 1 (1999)
5. (e) B. Rickborn, In Advances in Theoretically Interesting Molecules, R. P. Thummel, Ed., JAI Press, Greenwich, 1989, Vol. 1, pp 1-134