@article{Waelkens:1916,
      author        = "Waelkens, C. and  Lampens, P. and  Heynderickx, D. and 
                       Cuypers, J. and  Degryse, K. and  Poedts, S. and  Polfliet,
                       R. and  Denoyelle, J. and  van den Abeele, K. and  Rufener,
                       F. and  Smeyers, P.",
      title         = "{Geneva photometry of stars in the double cluster H and
                       Chi Persei}",
      year          = "1990",
}