@article{phien:1990:ncb,
    author = {Phien, H. N.},
     title = {A note on the computation of the incomplete beta
              function},
   journal = {Adv. Eng. Software},
    volume = {12},
      year = {1990},
    number = {1},
     pages = {39–44},
      note = {Includes Basic code.},
       doi = {10.1016/0141-1195(90)90040-D}}