Th. Jacobs, S. O. Katterwe, H. Motzkau, A. Rydh, A. Maljuk, T. Helm, C. Putzke, E. Kampert, M. V. Kartsovnik, V. M. Krasnov: Electron-tunneling measurements of low-T-c single-layer Bi2+xSr2-yCuO6+delta: Evidence for a scaling disparity between superconducting and pseudogap states. 2012Physical Review B: 86. ISBN 1098-0121 http://dx.doi.org/10.1103/PhysRevB.86.214506