Gardner, Adrian M., Tuttle, William D., Groner, Peter, Wright, Timothy G., "Molecular symmetry group analysis of the low-wavenumber torsions and vibration-torsions in the S1 state and ground state cation of p-xylene: an investigation using resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy", Journal of Chemical Physics,