S. L. Anderson, L. Goodman, K. Krogh-Jespersen, A. G. Ozkabak, R. N. Zare, and C. F. Zheng,”Multiphoton Ionization Photoelectron Spectroscopy of Phenol: Vibrational Frequencies and Harmonic Force Field for the 2B1 Cation,”J. Chem. Phys. 82, 5329-5339 (1985).