@article{Tooper:1968:SCE,
author = {Tooper, R. F. and Mark, J.},
title = {Simplified calculation of $\mathrm{Ei}(x)$
for positive arguments, and a short table of $\mathrm{Shi}(x)$},
journal = {Math. Comp.},
volume = {22},
year = {1968},
number = {102},
pages = {448–449},
links = {\URL[FullText]{http://links.jstor.org/sici?sici=0025-5718%28196804%2922%3A102%3C448%3ASCOFPA%3E2.0.CO%3B2-J}},
doi = {10.2307/2004679},
zblno = {0153.46801}}