The Brian Carpenter paper that was cited before with URL for
the official publication site
https://doi.org/10.1016/0169-7552(89)90040-8
which leads to the Elsevier paywall, can be accessed for
free in its preprint form at
https://cds.cern.ch/record/197332/files/CM-P00059917.pdf
Andrew
P.S. With thanks to Google Scholar.