R. Hackl, M. Opel, PF. Muller, G. Krug, B. Stadlober, R. Nemetschek, H. Berger, L. Forro: Electronic Raman scattering in CuO2 superconductors. 1996Journal of Low Temperature Physics: 105. ISBN 0022-2291 http://dx.doi.org/10.1007/BF00768471