@article{filho:1967:gfa,
    author = {Filho, A. M. S. and Schwachheim, G.},
     title = {Algorithm 309. Gamma function with arbitrary precision},
   journal = {Comm. ACM},
    volume = {10},
      year = {1967},
    number = {8},
     pages = {511–512},
      issn = {0001-0782},
       doi = {10.1145/363534.363561}}