String structures in driven 3D complex-plasma clusters L. Wörner, C. Räth, V. Nosenko, S. K. Zhdanov, H. M. Thomas, G. E. Morfill, J. Schablinski and D. Block EPL, 100 3 (2012) 35001 Published online: 13 November 2012 DOI: 10.1209/0295-5075/100/35001