Chain formation by spin pentamers in η-Na9V14O35 D. V. Zakharov, H.-A. Krug von Nidda, J. Deisenhofer, F. Schrettle, G. Obermeier, S. Horn and A. Loidl EPL, 83 6 (2008) 67002 Published online: 02 September 2008 DOI: 10.1209/0295-5075/83/67002