@article{todd:1954:eei,
    author = {Todd, John},
     title = {Evaluation of the exponential integral for large complex
              arguments},
   journal = {J. Research Nat. Bur. Standards},
    volume = {52},
      year = {1954},
     pages = {313–317},
   mrclass = {65.0X},
  mrnumber = {MR0061475 (15,832b)},
mrreviewer = {H. B{\"u}ckner},
     zblno = {0055.36002}}