STM studies of the surface structure in cleaved single crystalsL. Shan, A. Ejov, A. Volodin, V. V. Moshchalkov, H. H. Wen and C. T. LinEurophys. Lett., 61 5 (2003) 681-687DOI: https://doi.org/10.1209/epl/i2003-00130-3