1. G. A. Blake, in Encyclopedia of Chemical Physics and Physical Chemistry, vol. 2, J. H. Moore, N. D. Spencer, eds. IOP (2001), p. 1063.
2. Millimeterwave and Submillimeterwave Laboratory Spectroscopy in Support of Observational Astronomy
3. Population Diagram Analysis of Molecular Line Emission
4. For Herschel Space Observatory data, see https://archives.esac.esa.int/hsa/whsa.
5. For data from the Stratospheric Observatory for Infrared Astronomy, see www.sofia.usra.edu/data/science-archive.