@article{Nakos:1934,
      author        = "Nakos, T. and  Ofek, E. O. and  Boumis, P. and  Cuypers,
                       J. and  Sinachopoulos, D. and  van Dessel, E. and  Gal-Yam,
                       A. and  Papamastorakis, J.",
      title         = "{A catalog of secondary photometric standard stars around
                       gravitational lenses}",
      year          = "2003",
}