@article{noble:2004:whw,
    author = {Noble, C. J.},
     title = {Evaluation of negative energy {C}oulomb ({W}hittaker)
              functions},
   journal = {Comput. Phys. Comm.},
  fjournal = {Computer Physics Communications},
    volume = {159},
      year = {2004},
    number = {1},
     pages = {55–62},
      note = {Double-precision Fortran-90 code.},
       doi = {10.1016/j.comphy.2003.12.004},
     links = {\URL[Code]{http://cpc.cs.qub.ac.uk/summaries/ADSZ}}}