1. S. Daniel, M. Chaudhury, P.-G. de Gennes, to be published in Langmuir.
2. A. Buguin, F. Brochard and P.-G. de Gennes, to be published in European Journal of Physics E.
3. P. Langevin, CR Acad. Sci. (Paris) 530 (1908).
4. M. von Smoluchowski, work described in Physical Chemistry, S. Berry, S. Rice, J. Ross eds. (Wiley NY, 1980), p. 1164.