Confocal microscopy of geometrically frustrated hard sphere crystals R. P. A. Dullens, V. W. A. de Villeneuve, M. C. D. Mourad, A. V. Petukhov and W. K. Kegel Eur. Phys. J. Appl. Phys., 44 1 (2008) 21-28 Published online: 22 July 2008 DOI: 10.1051/epjap:2008145