@article{adamchik:1998:pgf,
    author = {Adamchik, Victor S.},
     title = {Polygamma functions of negative order},
   journal = {J. Comput. Appl. Math.},
  fjournal = {Journal of Computational and Applied Mathematics},
    volume = {100},
      year = {1998},
    number = {2},
     pages = {191–199},
      issn = {0377-0427},
     coden = {JCAMDI},
   mrclass = {33B15 (33C60 65D20)},
  mrnumber = {MR1659113 (99j:33001)},
       doi = {10.1016/S0377-0427(98)00192-7},
     zblno = {0936.33001}}