NIST Chemistry WebBook
Recommended citation for data from M.E. Jacox:
Data in the WebBook should be cited as though they are in a series of chapters in a book. The individual chapters are not the pages of data on a single molecule but rather the collection of data of a particular type. The "book" containing these chapters is the NIST Standard Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard.
The citation for data from M.E. Jacox should be as follows:
M.E. Jacox, "Vibrational and Electronic Energy Levels of Polyatomic Transient Molecules" in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard, National Institute of Standards and Technology, Gaithersburg MD, 20899, doi:10.18434/T4D303, (retrieved September 19, 2018).