# source of the Sellmeir coefficients
Air, Nitrogen, Helium, Neon, Argon, Krypton, Xenon : A. Börzsönyi et al. "Dispersion measurement of inert gases and gas mixtures at 800 nm" (2008)
Silica :  I. H. Malitson. Interspecimen comparison of the refractive index of fused silica (1965)

In sellmeierRefractiveIndex : see refractiveindex.info

Van der Waals constants from https://en.wikipedia.org/wiki/Van_der_Waals_constants_(data_page)

Chi3 : Wahlstrand 2012

