Differential interference contrast X-ray microscopy with twin zone plates at ESRF beamline ID21 T. Wilhein, B. Kaulich, E. Di Fabrizio, F. Romanato, M. Altissimo, J. Susini, B. Fayard, U. Neuhäusler, S. Cabrini et F. Polack J. Phys. IV France, 104 (2003) 535-541 DOI: 10.1051/jp4:20030139