1. Selected reviews: (a) J. Issberner, R. Moore, F. Vögtle, Angew. Chem. 107 (1994) 2507. (b) J. Issberner, R. Moore, F. Vögtle, Angew. Chem. Int. Ed. Engl. 33 (1994) 2413. (c) G.R. Newkome, Advances in Dendritic Macromolecules, vol. 1, Jai, London, 1994. (d) M.K. Lothian-Tomalia, D.M. Hedstrand, D.A. Tomalia, A.B. Padias, H.K. Hall, Jr., Tetrahedron 53 (1997) 15495. (e) J.W. Kriesel, S. König, M.A. Freitas, A.G. Marshall, J.A. Leary, T.D. Tilley, J. Am. Chem. Soc. 120 (1998) 12207. (f) J.W.J. Knapen, A.W. van der Made, J.C. de Wilde, P.W.N.M. van Leeuwen, P. Wijkens, D.M. Grove, G. van Koten, Nature 372 (1994) 659. (g) M.A. Hearshaw, J.R. Moss, Chem. Commun. (Cambridge) (1999) 1.
2. (a) Y.H. Kim, Adv. Matter 4 (1992) 764.
3. (b) D.A. Tomalia, A.M. Nayler, A. Goddard III, Angew. Chem. 102 (1990) 119.
4. (c) ibid, Angew. Chem. Int. Ed. Engl. 29 (1990) 138.
5. (d) T.K. Lindhorst, Nachr. Chem. Tech. Lab. 44 (1996) 1073.