@article{GDZPPN001177745,
title = {The Numerical Computation of the Confluent Hypergeometric Function U(a,b,z)},
journal = {Numerische Mathematik},
volume = {42},
year = {1983},
pages = {63-82},
zbl = {0489.33001},
url = {http://dml.mathdoc.fr/item/GDZPPN001177745}
}
Temme, N.M. The Numerical Computation of the Confluent Hypergeometric Function U(a,b,z). Numerische Mathematik, Tome 42 (1983) pp. 63-82. http://gdmltest.u-ga.fr/item/GDZPPN001177745/