@article{vanHoof:2133,
      author        = "van Hoof, P. A. M. and  Williams, R. J. R. and  Volk, K.
                       and  Chatzikos, M. and  Ferland, G. J. and  Lykins, M. and 
                       Porter, R. L. and  Wang, Y.",
      title         = "{Accurate determination of the free-free Gaunt factor - I.
                       Non-relativistic Gaunt factors}",
      year          = "2014",
}