@article{walker:2007:zep,
    author = {Walker, Peter L.},
     title = {The zeros of {E}uler's psi function and its derivatives},
   journal = {J. Math. Anal. Appl.},
  fjournal = {Journal of Mathematical Analysis and Applications},
    volume = {332},
      year = {2007},
    number = {1},
     pages = {607–616},
      issn = {0022-247X},
     coden = {JMANAK},
   mrclass = {33B99 (30C15)},
  mrnumber = {MR2319687 (2008a:33002)},
       doi = {10.1016/j.jmaa.2006.10.050},
     zblno = {1112.33016},
zblreviewer = {Mehdi Hassani}}