Density-dependent pair interactions in 2D colloidal suspensions M. Brunner, C. Bechinger, W. Strepp, V. Lobaskin and H. H. von Grünberg Europhys. Lett., 58 6 (2002) 926-965 Published online: 01 June 2002 DOI: 10.1209/epl/i2002-00105-4