Reference Label	Details
Herzberg 1966	G. Herzberg, "Molecular Spectra and Molecular Structure. III. Electronic Spectra and Electronic Structure of Polyatomic Molecules", Van Nostrand Reinhold: New York 1966
est unc	estimated uncertainty
Smith 1962	D. Smith, A. H. Nielsen, B. P. Stoicheff, and G. W. Robinson, in: Methods in Experimental Physics. Molecular Physics, D. Williams, ed., vol. 3, pp. 7-264, Academic Press: New York 1962 Molecular Spectroscopy