"R. Schuster,S. Pyon,M. Knupfer,M. Azuma,M. Takano,H. Takagi,B. BNuchner","Angle-dependent spectral weight transfer and evidence of a symmetry-broken in-plane charge response in Ca?.?Na?.?CuO?Cl?",,"PHYSICAL REVIEW B",,"Vol. 86","No. 245112","pp. 1-6",2012,Dec. "R. Schuster,S. Pyon,M. Knupfer,J. Fink,M. Azuma,M. Takano,H. Takagi,B. Buchner","Charge-transfer excitons in underdoped Ca2-xNaxCuO2Cl2 studied by electron energy-loss spectroscopy",,"Phys. Rev. B",,"Vol. 79",,"pp. 214517-1-4",2009,