Survey response rates: National and regional differences in a European multicentre study of vertebral osteoporosis

T. W. O'Neill, D. Marsden, C. Matthis, H. Raspe, A. J. Silman, D. Agnusdei, K. Bergmann, C. Cooper, J. Dequeker, D. Felsenberg, J. A. Kanis, G. Kruskemper, T. Lauermann, K. Weber, P. Geusens, I. Jajic, S. Havelka, P. Vavrincova, P. D. Delmas