I guess this will keep happening as you hinted at in #11. Maybe it makes sense to include other reference fields in the output files, such as the DOI itself and the title of the publication? Users could then still find the reference in case the URL is dead.
All of them point to the same URL: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.465.8749&rep=rep1&type=pdf which shows the message "Token is required".
I guess this will keep happening as you hinted at in #11. Maybe it makes sense to include other reference fields in the output files, such as the DOI itself and the title of the publication? Users could then still find the reference in case the URL is dead.