@article{Clette:310,
      author        = "Clette, F. and Berghmans, D. and Vanlommel, P. and Van der
                       Linden, R.A.M. and Koeckelenbergh, A. and Wauters, L.",
      title         = "{Du Nombre de Wolf a l'indice international des taches
                       solaires: 25 ans de SIDC (2ème partie)}",
      year          = "2008",
}