V. B. Zabolotnyy, S. V. Borisenko, A. A. Kordyuk, J. Geck, D. S. Inosov, A. Koitzsch, J. Fink, M. Knupfer, B. Buechner, S. -L. Drechsler, H. Berger, A. Erb, M. Lambacher, L. Patthey, V. Hinkov, B. Keimer: Momentum and temperature dependence of renormalization effects in the high-temperature superconductor YBa2Cu3O7-delta. 2007Physical Review B: 76. ISBN 1098-0121 http://dx.doi.org/10.1103/PhysRevB.76.064519