@article{Amos:1983:PFS,
author = {Amos, D. E.},
title = {Algorithm 610. {A} portable {FORTRAN} subroutine for
derivatives of the psi function},
journal = {ACM Trans. Math. Software},
fjournal = {Association for Computing Machinery. Transactions on
Mathematical Software},
volume = {9},
year = {1983},
number = {4},
pages = {494–502},
note = {Single and double precision, maximum accuracy 18S.},
issn = {0098-3500},
coden = {ACMSCU},
mrclass = {65D20},
mrnumber = {MR0791979},
doi = {10.1145/356056.356065},
links = {\GAMSmodule{TOMS}{610}{8648}},
zblno = {0519.65013}}