Reference Label	Details
NIST Atomic Web	NIST Atomic Spectra Database, NIST Standard Reference Database #78, National Institute of Standards and Technology: Gaithersburg, MD 2002 Web: http://physics.nist.gov/cgi-bin/AtData/main_asd
Moore 1970	C. E. Moore, "Ionization Potentials and Ionization Limits Derived from Analyses of Optical Spectra", NSRDS-NBS 34, National Bureau of Standards: Washington, DC 1970
Eriksson 1968	K. B. S. Eriksson and H. B. S. Isberg, Ark. Fys. 37, 221-230 (1968) New Measurements in the Spectrum of Atomic Oxygen, O I