@misc{NIST:DLMF,
         key = "{\relax DLMF}",
       title = "{NIST Digital Library of Mathematical Functions}",
howpublished = "http://dlmf.nist.gov/, Release 1.0.6 of 2013-05-06",
         url = "http://dlmf.nist.gov/",
        note = "Online companion to \cite{Olver:2010:NHMF}"}

@book{Olver:2010:NHMF,
      editor = "F.~W.~J. Olver and D.~W. Lozier and R.~F. Boisvert and C.~W. Clark",
       title = "{NIST Handbook of Mathematical Functions}",
   publisher = "Cambridge University Press",
     address = "New York, NY",
        year = "2010",
        note = "Print companion to \cite{NIST:DLMF}"}