@article{rosengren:1999:apt,
    author = {Rosengren, Hjalmar},
     title = {Another proof of the triple sum formula for {W}igner
              {$9j$}-symbols},
   journal = {J. Math. Phys.},
  fjournal = {Journal of Mathematical Physics},
    volume = {40},
      year = {1999},
    number = {12},
     pages = {6689–6691},
      issn = {0022-2488},
     coden = {JMAPAQ},
   mrclass = {81R05 (33C80)},
  mrnumber = {MR1725880 (2000j:81089)},
mrreviewer = {Michael W{\"u}stner},
       doi = {10.1063/1.533114},
     zblno = {0967.81032}}