1. Refractive index: CO2;Michels;Physica,1937
2. N2: A. Michels, H. and L. Lebesque and S. R. de Groot
3. C2H4: A. Michels, A. Botzen and S. R. de Groot, to be published soon.
4. Dielectric constant: CO2;Michels;Physica,1939
5. Dielectric constant: N2;Michels;Phil. Mag.,1932