1. Baxter, P., Lehn, J.-M., DeCian, A. & Fischer, J. Angew. Chem. Int. Ed. Engl. 32, 69–72 (1993).
2. Vögtle, F. Supramolecular Chemistry (Wiley, Chichester, 1991).
3. Constable, E. C. Tetrahedron 48, 10013–10059 (1992).
4. Dietrich-Buchecker, C. O. & Sauvage, J.-P. Bioorganic Chem. Frontiers 2, 197–248 (1991).
5. Constable, E. C. & Walker, J. V. J. chem. Soc., chem. Commun., 884–886 (1992).