1. Belanger, A., Brassard, P., Laquerre, S. and Merand, Y. (1987) Corn. J. Chem. 65, 1392–1396.
2. Bergman, I., (1968) Nature 218, 396.
3. Borman, S.A. (1981) Anal. Chem. 53, 1616A–1618A.
4. Eichhorn F., Rutenberg, A. and Kott, E., (1971) Clin. Chem. 17, 296.
5. Guilbault G.G. et al (1967) Anal. Chem. 39, 271, (1968) ibid.