1. Proe. Roy;Buckingham R. A.;Soc. A,1938
2. Eath P. G. & Onnes H. K. 1923 Commun. Phys. Lab. Univ. Leiden no. 156a.
3. Chapman S. & Cowling T. G. 1939 Mathematical theory of non-uniform gases formula 10.21.1. Cambridge University Press
4. Z. phys;Chem. B,1936
5. Z. phys;Elusius K.;Chem. B,1940