Verification of {\Gamma}$_{7}$ symmetry assignment for the top valence   band of ZnO by magneto-optical studies of the free A exciton state
  The circularly-polarized and angular-resolved magneto-photoluminescence spectroscopy was carried out to study the free A exciton 1S state in wurtzite ZnO at 5 K. 
Lu Ding, Chunlei Yang, Hongtao He, Fengyi Jiang, Jiannong Wang, Zikang   Tang, Bradley A. Foreman, and Weikun Ge
cond-mat.mes-hall