One entry per version
A working paper and a journal article can share a title while differing in sample, methods or appendices. Record the version and date you actually read. Keep the repository or publisher URL beside your notes so you can later check whether a correction or newer version changes a passage you cited.
Preserve a calculation trail
Write units, transformations and assumptions beside any number you copy or calculate. If a chart uses a different period from the main table, record that difference explicitly. Small notes at the time of reading prevent later comparisons from silently mixing incompatible quantities.
Handle missing files honestly
The historical backlinks include a business-statistics book file and two research PDFs. Their exact original bytes have not been recovered in this build, so those file addresses remain unavailable. Search a verified author, institutional repository or publisher catalogue by title; a filename is not enough evidence to recreate a paper.
