Reference Label	Details
Nicholson 1965	A. J. C. Nicholson, J. Chem. Phys. 43, 1171-1177 (1965) Photoionization-Efficiency Curves. II. False and Genuine Structure
Nicholson 1963	A. J. C. Nicholson, J. Chem. Phys. 39, 954-961 (1963) Photo-Ionization Efficiency Curves. Measurement of Ionization Potentials and Interpretation of Fine Structure