1. T. Graham: Philos. Mag. 136, 573 (1846); 153, 385 (1863); see also
2. R.Jackson: Transport in porous catalysts (Elsevier, Amsterdam 1977) p. 186ff.
3. M.Knudsen: Ann. Phys. 28, 75 (1909)
4. J.C.Maxwell: Scientific Papers, ed. by W.D.Niven (Cambridge University Press 1890, and Dover, New York 1965)
5. W. Ramsey: Nature 52, 7 (1895)