Frost, R.L., Palmer, S.J., Cejka, J., Sejkora, J., Plasil, J., Bahfennea, S. and Keeffe, E.C. (2011) A raman spectroscopic study of the different vanadate groups in solid-state compounds-model case: Mineral phases ve-signieite [BaCu3(VO4)2 (OH)2] and volborthite [Cu3V2O7(OH)2•2H2O]. Journal of Raman Spectroscopy, 42, 1701-1710.