M. Grayson, M. Huber, M. Rother, W. Biberacher, W. Wegscheider, M. Bichler, G. Abstreiter: Experimental demonstration of a sharp quantum Hall edge. 2004Physica E-Low-Dimensional Systems & Nanostructures: 25. ISBN 1386-9477 http://dx.doi.org/10.1016/j.physe.2004.06.019